Funny you should mention Choco/Mog; my suggestion happens to be just that.
Choco/Mog
Basically, a moogle riding a chocobo. Unlike another pair, the Ice Climbers, these two are inseperable and work in tandem. Chocobo does the majority of the fighting, but Mog (in other words, the moogle) helps with special attacks, holds items and weapons, and does use a few melee attacks.
Statistically, Choco/Mog leans toward the light, speedy type, perhaps on par with Fox. Physically, they look most like the Chocobo and Moogle seen in Final Fantasy VI.
Melee:
standard - right wing slash, left wing slash
forward - talon kick
F-smash - magic shock
downward - tailfeather sweep
D-smash - magic quake
upward - beak swipe
U-smash - overhead shock
running - tackle
aerial standard - talon rake
aerial downward - nosedive
aerial forward - talon axe
aerial upward - upward shock
aerial rear - rear shock
Grab/Throws:
Grab - magic manipulation
Throw Forward - chocobo kick
Throw Upward - rocket toss
Throw Downward - talon stomp
Throw Backward - chocobo spin kick
Standard Special - Aero
Mog casts Aero, which surrounds the duo and knocks opponents away. Can be charged for greater power, although the longer the Special is charged, the longer it must recharge before you can use it again. Can also be charged while running and jumping.
Forward Special - Thief Dash
Choco/Mog dash forward at a blinding speed, dealing minimal damage, and if the opponent is carrying an item (such as the Beam Sword), they take it for themselves, unless they already carry an item. Powerups such as Bunny Hood and Metal Box cannot be stolen.
Downward Special - Dig Frenzy
Chocobo thrashes the ground with his beak, damaging anyone caught (and burying them if they`re grounded) and occasionally uprooting an item.
Upward Special - Dragoon Jump
Choco/Mog shoots straight upward, pauses for a second, then shoots straight back down or to either side, depending if the player is holding left, right, or neither. When used in air, Choco/Mog simply pauses before shooting down, rather than shooting upward beforehand.
Final Smash - Actually, I have two ideas for what could be the FS:
Golden Chocobo
Mog summons golden armor that attaches to Chocobo`s wings, legs, body and head temporarily, boosting speed and power as well as allowing you to control your height by holding jump to ascend and releasing jump to descend. You also stay suspended in mid-air when using aerial attacks. Take note that Choco/Mog can still be damaged.
Meteor
Mog summons a rain of meteorites that crash down upon the field, damaging anyone caught in the storm. Small meteorites cause little damage and do not flinch, medium meteorites cause mild damage and do flinch, and large meteorites cause great damage and send opponents flying.
Which one sounds better?