Smeargle would merely be a second Togepi... Which I have no problem with. I'd imagine it'd have half weak moves, half strong moves, and a thoroughly rare attack of instantaneous death (ohai Porygon2 from melee) as well as a useless move in splash.
Speakin' of gimmicks, Ditto was s'posed t' be in Melee y'know. I think it'd be pretty interestin'. When sent out, it could randomly transform into any fighter, currently bein' played or not, at random. Once transformed it gets it's own invisible damage percentage 'n can be attacked and even knocked off the stage like any other player (team attack will always be off though). It'l act as a high level CPU 'till it's used 20 moves total, in which it'l transform back and disappear. There'd be a ridiculously low chance it'l turn into the Master Hand or somethin' and the match would continue as the Hand ravages the battlefield for 20 moves.