SSBM IS WICKED AWESOME!! THESE ARE MY FAVORITE PARTS OF THE GAME!
There's enough modes for you to be playing for about an entire day! Yup, it's that fun. Anyway, in 1-player mode, you can take Classic challenge, Adventure challenge, and later All-Star challenge. You can also do Training mode in which you pick a character for yourself (duh), and another character as your opponent, then pick a stage. You can choose Evade, Attack, Human, Walk, Stand, Jump and that's about it. you can also pick different items in the Training menu, and choose 1-3 opponents.
In melee, you can fight up to four players, Normal Melee, and Team Melee. There's also Tournament mode wher there can be up to 64 battles and 128 competetors (talk about crowded!). In Team Melee players form teams and fight against each other.
Maybe i'll write some more info on SSBM soon.... until then adios!