Forward...
First and foremost I'd like to get these details out of the way. In my vision of a Flash series it would be about Wally's career as The Flash. We would be introduced to the Flash as Wally, after Barry has already died. This is my choice because A) I like Wally better than Barry, and I think he's an all around better character, and B) I absolutely don't want to go through any origin bull crap, and I don't want to go through any sidekick phase and all that.
The only way I would make the movie about Barry is if DC got their shit together with their movies. If they actually had solid plans for their movies like Marvel does with the whole Avengers series, and planned to have a Flash, WW, Superman movie and then a Justice League tie in, I would say go right the hell ahead, and use Barry. Because then you could have a good one or two movies with him before the JLA movie in which they would need to kill him off, then Wally would take over and so on. But, seeing as DC only cares about Batman movies and doesn't give a damn about making any others, my Flash series would star Wally.
Movie 1: The Flash
Basically the first movie would be all about Wally becoming The Flash. By the beginning it will have already been, lets say a few months to a year since Barry's death. I think I would have this movie be kind of like the Crossfire arc. See, it wasn't really until Johns' run that the Rogues statred being a team and stuff. So there's no way you could start this series out with them already like that. I figure it would go something like this: The Flash just died, and all that's left to maintain order is his sidekick.
All the bad guys think that now they can run wild because they don't see Wally as a real threat. However, Wally is doing an adequate job of proving them otherwise. So, it would show him throwing a couple of them in jail, and they'd all be sitting in the lunch room at Iron Heights telling their story how the new Flash thwarted them. Then they would be approached by Abra Kadabra who would tell them that the reason they always got pwnd by the Old Flash and why they continue to is because they are too weak or whatever individually and that they should work together. So they stage a breakout and a metric ass ton of villains escape.
The they'd start terrorizing the city and Wally would be desperately trying to stop them but failing at their combined strengths. This is where we would be introduced to Wally's feelings of inadequacy to Barry and how he doesn't think he can live up to him and whatnot.
At one point, there would be a scene where the Rogues are comitting some crime, and in the process some innocent bystanders get killed or something, and at that point Cold/MM/Wizard and Heat Wave all say we don't do this kinda work, and Abra puts them all under mind control, but Cold manages to escape. At some point in the film, there would be a scene involving Wally visiting Jay Garrick like Dan does with Hollis in Watchmen, asking him some advice and whatnot, maybe mentioning Jay coming out of retirement.
Eventually Abra & Co take hold of the Channel 5 News building where Linda and some others become hostages. Abra then reveals his true intentions and uses the station just so he can broadcast himself across the nation so he can make a grand performance, some of the rogues get pissed and he turns them into puppets. Flash shows up and gets his ass kicked for a bit by all the Rogues, at which point Jay [frick]ing Garrick shows up to lend him a hand.
They fight a few of the Rogues then Jay says he'll hold them off, Wally then goes and takes down Abra and busts all his technology and crap, reversing his magic and leaving him powerless. Once this happens, the mind controlled Rogues are fee, and they ditch, and the others who were puppets get captured.
The movie ends with the city being all happy, Linda and Wally getting together after he rescued her, etc. The escaped Rogues would be approached by Cold who would say basically the same as in the Crossfire Arc "time for the Rogues to get a real leader" or something.
And right near the end it would need to show Abra in prison weeping while trying to do petty card tricks like at the end of that one arc.
(Details: In this movie of course it would have to make mention a few key things about Abra's hard-on for theatrics, and some stuff about Wally wanting to honor Barry's memory and such, as well as Cold's views on criminal behavior.
I think during the opening sequence, Wally would be wearing one of Barry's suits, but after it getting damaged, he goes to STAR labs and talks to Tina Mcgee about getting a new suit, and afterwards he'd be wearing his regular design.
Also, it would make mention of Wally winning the lottery, and him using the bulk of the money to create the Flash Museum and the Barry Allen Foundation.)
Film 2: The Fastest Man Alive
I'm thinking that after the ending of the first film, a good follow up would be something along the lines of Rogue War. Now that Cold has gotten his primary team of Heat Wave, Weather Wizard, Trickster and Mirror Master together, it could show how effectively they work together as a team. And you could include a bunch of stuff about their workings like Cold beating the crap out of MM and telling him no drugs. Meanwhile, another group of Rogues are terrorizing the city, and eventually the two groups duke it out, and have a full scale battle right in the middle of Keystone, and only The Flash can put an end to it.
There would absolutely need to be a secondary plot in the film, because just the part with the Rogues wouldn't be enough to fill the whole movie. I think I'd want to do something along the lines of Terminal Velocity, and introduce the speedforce into the movies, however, I'm not sure if I'd want to do that before the "Return" film.
Have some stuff about Wally feeling all weird from going to fast or some such, and possibly even have a scene where he turns all electricy and whatnot. It would also be a good way to introduce STAR Labs, Wally could go in to get some tests run and stuff, and they could say how they also treated Barry back in the day and introduce some theories on the speedforce and so forth.
It could then have the same conclusion as terminal velocity, with some imminent threat to Linda's life, and Wally rushing to save her, he ends up breaching the speedforce in the process, and everyone thinks he's dead, but then he comes back all ubercharged and sends the Rogues running.
ALTERNATE SECONDARY PLOT
Could be just like Blitz, the introduction of Zoom. During the terrorization of the city, Hunter gets his legs [frick]ed up, and beseeches Wally to help fix them, yada yada, then during the final confrontation between the Rogues, Zoom shows up and starts beating them down and sets his sights on Wally and whatnot. Ends with either Wally forcing Zoom into the Speeforce like Savitar, then coming back like in Terminal Velocity, or ends with Wally Infinite Mass Punching Zoom, after Jay lends him his speed energy.
The movie would have to end with a scene where Barry appears at Wally's door, setting it up for the third movie.
Film 3: The Return of Barry Allen
The 3rd movie would be The Return of Barry Allen. I think that it would easily be able to follow the plot of the arc from the comic, with only a few alterations. Start with Barry explaining how he came back, and theorizing that when Wally breached the Speedforce, it somehow cause some space time fluctuation that resulted in Barry's return. Have Wally and Barry going out, fighting crime and being pals and such.
Then just as in the comic, someone would deal a blow to Wally that would seemingly kill him, but he narrowly escapes, then as the bad guy is shouting "I KILLED THE FLASH" Barry would beat the hell out of him and respond with "I'M THE FLASH" Eventually they'd end up in the shrinking force field, and after Barry escapes, he leaves Wally to die. And this would be the first time in the films Wally would ever successfully vibrate through something.
At this point, we could have an awesome tie-in with the Green Lantern movies because Hal has a fight with Barry in that arc. So Hal could substitute for Jay and Max and fight Barry as he's terrorizing the city. And that was around the time he was getting all white haired due to Parallax, and depending on how far along the GL films are at that point it could work quite well.
One key factor in this movie would be Linda's assessment that Wally is afraid to fight Barry because he's not afraid that he's not good enough to beat him, but that all along he's been afraid of surpassing Barry.
::SPOILERS AHEAD::
Then we'd have Wally discover the book belonging to Eobard Thawne, and the shocking realization that Barry isn't all that he seems. Then "Barry" threatens to kill Linda, Wally comes to the rescue, and cue the big final showdown at the Flash Museum. After a bit of a happy ending epilogue the end.
Details:
I know that throughout the first two movies I'd want to show certain things in flashbacks, concerning Wally's origin and Barry's death and various important things. I'd probably copy paste a few scenes directly from Born To Run like Wally's accident and first meeting with Flash. That along with a flashback of either Barry killing Thawne, or his own death would be pretty much the only ones I'd use for movie 1.
I think I'd mention something about Wally winning the lottery, except instead of just having him be rich and whatnot, I think I'd have it so that he used most of his money to fund the opening of The Flash Museum in Barry's honor.
I'd begin the series with Linda not being Wally's girlfriend yet, and she'd be acting like a bitch to him.
I'd want them to start off not liking each other then gradually go into the relationship like in the comics. Basically she'd be the damsel in distress at the end of the movie, and by the second film they'd be together. Same with Wally's attitude, he'd start off as a bit of an arrogant douche, but mature as the movies go on.
In movie two I'd make a specific point of using a flashback to show Wally trying to learn to vibrate through things, it would likely be scene specific. Ex: The bad guys catch him, and he needs to vibrate out of a sticky situation.
The reason I'd have that in there is because in Part 3, there's that big moment when "Barry" turns on Wally and leaves him in that shrinking force field and Wally has to try and vibrate out, that being the first time he ever successfully does it.
And throughout all the movies I'd keep constant with Wally's internal monologuing just like they have it in the comics. I think this would really help for the sake of exposition, it would allow for flashbacks and such to be wrapped up quickly because it would have someone telling the audience what happened as well as showing them.
And it would work for any time Wally's doing some awesome speed stuff, so he can explain what the hell is going on so the audience doesn't have to try and figure it out for themselves. Like explaining the Infinite Mass Punch or vibrating through things, catching bullets etc.
Also throughout the first two movies, there would be a constant referral to Wally's feelings of insecurity and inadequacy at not living up to Barry's name. The Rogues would all tell him that he's not as good as Barry was etc.
And there would be tons of awesome moments. I'd take a lot of awesome parts from across the ages of Flash history. Statuizing someone, Infinite Mass Punch, moving faster than teleportation, outracing death, if Black Flash made it into a movie. All kinds of crap.
And there's also possibility for an awesome manly tears moment when you could have Wally explaining the whole super speed thing and having to spend time in a world moving too slow for him.
And I would indeed have further films, most likely using Zoom as a villain. Hunter Zolomon would be introduced in movie 1 or 2 as a profiler mainly as an excuse to give background details on all the rogues.
Intro to film:
The movie would open with an exterior shot of the Flash Museum with a banner exclaiming "Grand Opening" or somesuch.
Outside the museum is Linda Park reporting on the opening of the museum.
Cut inside to show a group of people standing in front of a display and the curator talking about Barry Allen, when suddenly theres's an explosion or something and in comes Captain Boomerang and some thugs(or possibly another villain such as the trickster or some small time guy).
Boomerang starts giving a long winded villain speech, and then cut to the interior of a living room, with a news report about the incident on tv (Linda Park naturally doing the reporting)
[camera would be positioned behind the couch, only showing the back of a red haired man putting on a suit] Then there's a gust of wind, debri flys around the room.
Cut to a shot of a city street, cue voiceover: "My Name is Wally West." Then a red blur flys down the road, scattering litter, blowing peoples hair around etc.
Cut back to the museum, a hostage trys to run, so Capt. Tosses a 'rang at him/her, they are all "ohshi-" and putting up their arms and such, but then a red blur enters the scene and the hostage looks, amazed that hey aren't injured.
Zoom in to Capt. B and he's pissed and confused, the we hear a (wilhelm)scream, he looks around frantically to see a henchman unconcious, followed by more screams, and Boomerang looks around wildly,(each time the camera happens in the direction of the hostages, there's less of them) untill all his henchmen(or fellow villains) are dispatched, at which point he looks back to find the hostages gone, and The Flash standing before him. [this sounds like a lot, but it all hapens pretty quick]
Capt. scowls and unsheaths a boomerang, and throws it at Flash, who catches it and says something along the lines of "I thought you would've learned that doesn't work by now, Digger?" to which Boomerang responds "Seems you've got some learnin' ta do yerself, kid." and pulls out a detonator and pushes the trigger. Then Flash looks in shock and books it out of the museum(it would cut to slow motion for a bit to show him running as the bomb explodes in his hands) and then he tosses it where it explodes in the air, part of his costume is scorched from the explosion.
He runs back inside and Digger is angry that his trick didn't work, so he grabs another two boomerangs, but before he can do anything, Flash runs at him and the freezeframe as he punches Boomerang in the Face and the voiceover says "I'm the Fastest Man Alive."
Credits begin as the camera starts to pan away from the freezeframe and basically go on a tour of the museum, panning across displays, newspaper articles on the walls, monitors with vidoes of Flash rescuing people and whatnot, wax sculptures of Barry, Wally as kid flash, various Rogues ect. These would be essentially to give a a breif summary of Barry's exploits as the Flash.
Essential among these would be a display of Barry being struck by lightning, some newspaper articles with headlines that sum up important events in Barry's life ex: "The Flash, Hero of Central City", something about Kid Flash, "Iris West murdered by the villain Proffesor Zoom", "The Flash on trial" with some text about him snapping Zoom's neck, perhaps next to a picture of him and Zoom fighting or something. Then have some about a "crisis" that the Justice league is fighting or something.
I think Barry's death would have to be changed somewhat to avoid involving the Crisis on Infinite Earths shenanigans, and simplified as much as possible. Maybe just something about some extra terrestrial being that was threatening Earth.
Also "The Ballad of Barry Allen" would be playing during the credits.
After the credits, outside the Museum, Linda is reporting on the incident and Wally runs up for an interview.
Casting
So far my rudimentary casting for these movies is as follows:
Wally West - Chris Evans(If he wasn't already busy with Captain America)
Linda Park - Kristen Kreuk
Barry Allen - NPH
Captain Boomerang - Hugh Jackman
Captain Cold - Hugh Laurie
Mirror Master - Gerard Butler
Jared Morrilo - Benjamin Bratt
Fred Chyre - Mickey Rourke