On Melee mode when your on the character selection screen put your cursor near free for all then press A now you will be in team battle mode.
I think you can make her dressless but i don't know how to. Maybe someone else can answer this.
You can't unlock Shadow in SSBM. You can unlock Shadow in SSBB though, he is an assist trophy. In SSBB, you can use a texture hack on Sonic to make him look like Shadow and you can play as him.
No
No he is not.
No.
You can't get sonic in SSBM only in SSBB and in SSBB you get him at the subspace emissary near the end
no.
yes
No.
no you cannot be Mario in ssbm but you can be fire luigi which is the white color for luigi. in brawl you can be firemario
You can't
No , Only In SSBB