First unlock Sonic you can do that many ways the easiest being finishing the subspace emissary, Second play Sonic in Classic Mode and beat Classic Mode you will win the Sonic trophy after your done. Once you unlock all the characters you can play the all star mode and if you beat this with Sonic you will also get his final smash trophy.
Sonic is in SSBB.
no metel sonic in ssbb
the important thing about it is if you have 250 trophys, you get a new character and if you have all, you get a special prize.
You can't get sonic in SSBM only in SSBB and in SSBB you get him at the subspace emissary near the end
Sonic.
with the smash ball
No , Only In SSBB
No.
You cannot do this.
no
Sonic doesnt have any other costumes.
All character trophies are obtained by completing classic mode and all star mode.