In Mutant Maddness!, one player must be pokemon and one must be mutant pokemon. To tell if it is a mutant or not, mutants should say Mutant and then their name (ex: Mutant Charmander).
To play mutant madness, it is alot like pokemon cards. Instead of needing energy cards, you need to wait until a certain turn to use attacks. If it says 'Turn 1' before your attack, you can use it on any turn. Turn 0 must be a mistake, so notify me if you see a Turn 0. And for Turn: 2s you can use it on the second turn and every turn after that. The object is to lower every one of your opponent's pokemon/mutant pokemon. If you don't know how to play pokemon cards, then this game probaly isn't the one for you.