Peach's can be easily avoided by grabbing hold of a ledge...then it just heals opponents.
DK's is actually pretty lame...I saw a video on youtube and DK was just there banging the bongos and mario was on the other side of the stage just waiting for it to finish.
Not sure about Wario...sounds like he'll be pretty powerful and faster, which is quite good. If you're stupid enough to use the motorcycle, that's your problem.
Asking for the best FSA is more interesting...it's a more even competition.