Y = Attack
B = Jump
X = easy special move(Training mode only)
Down = crouch
Down & Y will perform a crouching attack, while Up & Y performs your character's combo finisher. Everyone has an attack with forward, forward & Y(Gambit and Beast's X button move in Training mode). Cyclops, Gambit & Psylocke have quarter circle forward(Down, Down/forward, forward) & Y moves (Cyclops' can be done mid jump, and it's his and Psylocke's X button move in Training mode). Psylocke and Wolverine have Dragon Punch(forward, forward/Down, Down, Down/forward & Y) moves(Wolverines X button move in Training mode). Beast, Psylocke, & Wolverine have dive attacks(jump with B, Down & Y)[Beast & Psylocke can use theirs to reach high objects. Aimed just right, they can continually bounce off enemies heads]. Beast can stick to ceilings with B, Up. Cyclops has a forward, forward/Down, Down & Y move. Gambit has an Up, Up & Y move. Wolverine can climb vertical walls, by jumping into them to stick to them, and Up/Down to climb.
So the structure of the game is unique for a beat 'em up. Everyone has an introductory stage, then once you're past that you start getting passwords. There's about 3 stages and 2 boss battles that anyone can be chosen to play through, some characters will be able to find alternate paths with their abilities, and then everyone has a unique final stage, just before the final boss battle. If Someone has done damage to the final boss, and then is killed by him, the damage remains when you meet him again.
If you lose a life, each character starting with 2, you start the stage over from the very beginning. It's not a very forgiving game, especially since if one character loses all their lives, it's game over. There are health restoration items, small and larger red X squares. There are also blue X squares that will give the player an extra life if they can collect 3. Sometimes there is a square with rotating pictures of the X-Men that also seems to be an extra life.
In Training mode, you're given 3 lives, instead of 2, to try your hand at the introductory stages.
Overall: Considering this comes from the same company behind the Final Fight series, and many games like it, this has a very different feel. It's on a single plane, 1 life to try entire stages, without being able to pick up where you just died, instant death chasm's(nothing new to beat 'em ups, but not typical of single plane beat 'em ups), etc. Worth looking into if you're a fan of the license, and are curious to see a different take on the genre, by the company that redefined it in the first place. Just be ready for a difficult game.