I played MvC2 for small periods of time back when we still had an arcade. I never got competitive, and getting into the meta game is just hard. I use any combination of Cyclops, Dr. Doom, Iron Man, Wolverine, Psylocke, Hulk, and Sentinel, knowing absolutely none of their combos.
The mechanics of the game will take some getting used to. Blocking properly, calling assist characters, knowing when and when not to attack, combos into combos into more combos, and the works. What you wanna start with is picking characters you’re comfy with and using them in Arcade mode until you’re blue in the face.
From there on it’s training mode and friendly spars till you catch on. Or you can take the easy road and block whilst calling your assists like you have no clue that there are other buttons on your controller. Then again… Just pick up cable.