I recently beat the original Chibi-Robo for the Gamecube again and I have to say, the absolute LEAST that can be done is to make Chibi-Robo an assist trophy. Picking up items and scrubbing the floor to make it more slippery is both directly in his character and completely in style of an AT.
In the chance that he does reach full playable status, however, he'd still be a pretty good addition. May I throw in my own two cents for bits of a moveset?
Neutral Special:
Garbage Disposal - His lid pops open and a random piece of trash comes out for him to throw, the properties and amount of damage depending on the trash.
Side Special:
Chibi-Blaster - Standard projectile, slightly homes up or down towards the opponent. Can be charged to stun the opponent if it hits.
Up Special:
Squirter - Sprays water out a squirter that propells Chibi-Robo upwards, leaving the ground beneath him wet and prone to making the opponent slip at the spot he launched from. In attention to detail, the Chibi-Copter can't fly upwards, meaning something like this would be a more sensible and unique recovery.
Down Special:
Charge - Holding down a charge regenerates Chibi-Robo's energy, affecting the strength of his moves.
Final Smash:
Giga-Robo - Chibi-Robo uses his radar to call upon Giga-Robo, who falls down right behind Chibi-Robo's position. The initial landing can bury opponents in the ground. Giga-Robo proceeds to stomp upon and grab opponents, finishing with a charged up "Giga-Blaster" before walking off the screen.
Up Smash: The Chibi-Copter pops out of his lid to quickly rotate and score multiple hits above him.
Side Smash: Whips out his toothbrush and rapidly scrubs the floor in front of him, doing multiple hits.
Down Smash: Uses a spoon to do heavy knockback in a concentrated area, very much like Lucas' Down Smash.
Grab: Stuffs the opponent into his head. Completely reasonable considering he can shove a pirate ship 50 times his size into that lid of his.
Grab Attack: Shakes up and down to throw the opponent around inside of him.
Up Throw: Launches the opponent straight upwards out of his lid.
Forward Throw: Pops the opponent out and lobs them forward like trash.
Back Throw: Pops the opponent out and takes a swing at them with his plug, batting them into the ground behind him.
Down Throw: Pops the opponent out, jumps up, grabs his plug, and thrusts it onto them for electrical damage.
Up Taunt: Dances similarly to one of his Boom Box animations in Chibi-Robo: Park Patrol.
Side Taunt:
His little "cleaning bonus" dance, including the song.
Down Taunt: Poses like Drake Redcrest, creating a small explosion behind him that does slight damage to opponents nearby.
Additionally, I can imagine that his plug, a trademark feature and mechanic of Chibi-Robo, could be picked up at any time you stand on it, acting like a limited-ranged throwing item. This could give an excuse to make Chibi's ground attacks a little bit more weak, promoting use of comboing with Chibi's plug instead. Bonus shenanigans if the opponent can pick up his plug to throw, too.
