Wally West...A Flash that many of us grew up with...taken from us with the relaunch in 2011. Replaced with a younger...better version of the classic Flash...Barry Allen
Wally is set to be reintroduced in April in the Flash Annual #3 as a Flash (seemingly) from the future...according to hints dropped by the writer of the comic...
The CW's Flash on the other hand uses the now all to familiar Grant Gustin as Barry Allen..a Flash who, as it would seem, will be the norm in the show. Many have said that their is an issue with the fact that Iris West, Wally's Aunt and Barry's love interest, is and has been cast as a black actress. This has led to many believing that Wally, when introduced will also be black...or half black...or even adopted...but what if the producers take a page from the New 52, which they already have by introducing a younger, lighter, happier Barry Allen, and skip over having Wally West as the Flash (assuming the show runs for a couple of seasons) and simply have Barry as the main flash and Bart as the kid flash they chose to introduce.
Maybe...if they chose to ever connect the TV shows and the cinematic universe...and go into exploring alternate realities...and future timelines...a New 52 version of Wally...but as of now I think it is safe to assume that they plan on having Barry as the Flash...and Bart as Kid Flash...
As for costume(s)...I think it is safe to assume that...
Barry will don something like this....(Credit to Creator)
And Bart (if introduced) will not wear his smallville style attire (thank god!!)
But Rather One of The Following (Not New 52 Style...Its too flashy(get it :D) and should be saved for a teen titans/ young justice show/movie where they all have similar new 52 style costumes