Speaking of a new Pokémon Trainer, am I the only one who thinks a Hoenn Trainer with Mudkip, Grovyle, and Blaziken would be GENIUS?!
That would be terrible. What would Mudkip do? The N/S specials I can think of but what would he do for standard attacks? how would he play given he's light and slow? What would his recovery be?
Grovyle would work, kinda sheik like with bullet seed for Needle Storm, a more dash like Leaf Blade and Acrobatics (perhaps with a short glide) for recovery cover all his major moves, so it'd be cool to see.
As for Blaziken it'd be yet another fast fighter, giving him no defensive pokemon; he'd kinda work as a character with Sky Uppercut for recovery, Blaze kick as a side B (aimable up to 45 degrees below each side maybe?) and obvious normal moves, but that leaves the neutral special blank...
Overall I think if a Hoenn trainer happened Torchic/Marshtomp/Sceptile would make more sense in terms of moveset:
Torchic could play floaty (it's a bird) with multiple jumps (again, bird, flappy little wing puffs) and pecks and scratches for standard moves. The throws would be difficult, but the claws can hold things, with Pecking them to bits as the jab. The neutral special is obvious: Ember (little flames that continue to burn after use). Fire spin could be up B, as a slight recovery shooting him upwards? or bounce with less fire and a ground pound on fall?. The Side B is the hard one, with lots of options, sand attack (mashable longer range jab like?), mirror move (reflector), quick attack (space animals stylee); they all fit the move set, and could work in the game; it's hard, but I'd probs pick sand attack.
Marshtomp would be the heavy fighter, throwing out powerful attacks, even his projectiles. Powerful punches and kicks for standards, arms to grab, and some cool moves for specials: N: Water Gun; it's kinda a given for a water type, though I think in return Squirtle should get bubble to trip people. S: Mud Shot; a projectile that slows the hit target down and covers them in mud, helping you close distance and get powerful hits in. The recoveries the hard one; whirlpool perhaps, spinning upwards with it? I honestly don't know... The Up-B makes it hard, but it works a lot easier than mudkip.
Sceptile would be Grovyle above, but Sceptile instead.
It's still a push, but they at least all play differently, also different types at different stages makes it more interesting too, to stand alongside Kanto.
I'm gonna add my thoughts on other Gens too, just in cut down forms.
Johto: Chikorita/Quilava/Feraligatr
Defensive/Fast/Powerhouse
Sinnoh: Piplup/Grotle/Infernape
Floaty/Defensive/Fast
As for Unova Emboar makes the most sense for stage 3 (heavy), but I kinda like the idea of Serperior wrapping people up with his grabs, being fast and grab happy. Samurott wouldn't really work I don't think; nothing for grabs..
If Emboar were stage 3 it'd follow that:
Oshawott/Servine/Emboar
ummm?/Fast/Powerhouse
If Serperior were stage 3:
Tepig/Dewott/Serperior
Defensive/Power?/Fast
Unova Trainer doesn't lend itself very well to smash bros.