Since the Hulk's MCU debut in Phase One's Incredible Hulk movie from 2008, Hulk was being pursued by Hulkbusters, and in the end defeated Abomination.
Now for this second film, new characters that Marvel Studios is most likely to include those that would adapt into the cinematic franchise less disturbing and more meaningful. Some of you were expecting Planet Hulk to happen as the second MCU Hulk movie, but with Joss Whedon and other officials denying those rumors, Planet Hulk is very much not gonna happen and besides, there is much more for Marvel Studios to have in store for Hulk in the next movie that involves staying on Earth.
For new characters that Kevin Feige and Marvel Studios is very much intended to use are those that can expressed meaningfully in the cinematic universe and some of them that can be expressed meaningfully are allies like Bruce Banner's cousin Jennifer Walters aka the She-Hulk
As Bruce's cousin, Jennifer Walters is a professional lawyer who was given an emergency blood transfer from Banner when she was wounded which led to her acquiring a milder version of his Hulk condition. As such, Walters becomes a large powerful green-hued version of herself while still largely retaining her personality. In order for her to appear in the sequel, Feige and Marvel Studios would express how Bruce Banner would make a huge risk in attempting to save the life of his love ones.
Now for those actresses that would make a fine She Hulk, these are the most popular choices
Megan Fox
Emmanuelle Chriqui
and Eliza Dushku
Villains that he would use that are more comfortable and less disturbing for Hulk to take on in the sequel are a specific group of villains composed of 4 different scientific elements known as
The U-Foes
And the best thing about the U-Foes is that they are described as an evil version of the Fantastic Four. Infact they have the same origin as the Fantastic Four as they were attempting to get their superpowers the same way Reed Richards and his team did but with different results.
Vector: Telikinesis
Vapor: Gaseous Matter
X-Ray: Radiation
Ironclad: Metal
To fit into the Marvel Cinematic Universe's Incredible Hulk sequel their origins will have to be changed just like the characters Ultron, Quicksilver, and Scarlet Witch.
Other supporting characters that are speculated to appear as Hulk's allies are
Hawkeye
and Rick Jones
until announcements are made in 2014, stay tuned for more updates on the film as they come