Marvel vs Capcom 3/Systems/Movement: Walking Jumping Crouching
To walk forward or backwards, just press the controller in the direction your character is facing (Towards) or in the opposite direction your character is facing (Back) respectively. To crouch, hold any of the three Down positions on the controller. And finally, for Jumping, you can jump in any of three directions: for a straight up jump, to jump backwards, or to jump forward.
Marvel Vs. Capcom 3 is all about movement. Your characters are rarely going to be standing still and the key to success in this game will come down to how well you can maneuver your character around the screen. And while, at higher levels, you will be spending most of your time Dashing and Super Jumping and Flying and Air Dashing and what-not, you'll never get anywhere without first growing accustomed to the three most basic forms of movement: Walking, Jumping, and Crouching.
It should be noted, though, that M.O.D.O.K. actually does not possess a Jump! Whenever you hit Up on the controller when using M.O.D.O.K., he goes into low flight mode instead.