Let's see.. Let's actually REWORK the CURRENT character's movesets, shall we?
I'd like the removal of tripping, and re-work movesets. Marth's tip thingy is really unfair to the newbies, so cut that, having Marth's sword tip do more damage than the rest of the blade seems a bit strange.
Remove that rediculous range DK has, seriously. He KO's from an arm's lengh away even if he punches. Fix that, but don't make it go under the fist either.
Give Sonic more control, he IS the fastest thing alive, but he never had to go full-speed to avoid traps, ala Sonic 1 ~ S3&K.
Pokemon Trainer should pick his three before the start of the battle before wasting his down+B move, really useless. Ivysaur's Bullet Seed could use more control as well, not play like Rospark in Megaman ZXA, in movement mode.
Have PK Thunder be a rebound move, instead of having to control it. Anyone caught in the PK Thunder should still have damage, but the move should continue to propel Ness foward, in other words, make Ness less gimmicky.
Lucario should have to be like other pokemon, having the one based off "Lucario and the Mystery of Mew", sounds annoying. Reminds me of a certain boss in the Megaman series when he goes "BEHOLD, MY TRUE POWER!".
Luigi's damaging taunt was a nice touch, but I'd say that it should apply to both bros.
Players imprisonated in Yoshi's egg should give the ability to roll for a change, to add a little fairness to beginners.
Make Bowser more like his M&L
S counterpart to make him more "special" to the franchise of Mario.
Reduce Peach's Princess Bomber's damage, it's a powerhouse, I tell ya.
Yep, mine was actually about tweaking existing movesets here, not the addition of characters n' shit.