If they modify any of the characters that have already been in Melee/Brawl, this is what I would want changed in SSB4:
Mario: FLUDD (after a full charge) can use any of it's modes.
Luigi: Can use the Poltergust 3000
Yoshi: Egg Roll no longer leaves you in a freefall. and launches you forwards when used in the air.
Bowser: Side B is now a mace. (Like in SMRPG)
Peach: Perry instead of Toad
Wario: Corkscrew can be aimed, and the bike can be damaged WHILE Wario is on it.
Donkey Kong: Headbutt becomes his new FSmash, with Barrell Throwing replacing SideB.
Diddy Kong: Throws rocks instead of bananas (just so he doesn't throw items already in the game as a move)
Dr. Mario: Uses his stethoscope as a chain, and his pills have varying effects (sleep, poison, etc.)
Roy: Counter becomes replaced with Spire, which is a wall of flame that jettisons out of his upraised sword. His FS would be Eruption, which is an explosion of flame around him that does high knockback.
Marth: Speaks English in the NA version. Counter becomes quicker after repeated use.
Ike: Has lightning effects instead of fire (to seperate him from Roy). Down B becones Discharge, which is like eruption but with sparks. Neutral B becomes Ion, which is a electric wave that has reflective properties around Ike. Great Aether would be the same, but he finishes off with a lightning bolt instead of a ground slam.
Pokemon Trainer: Pokemon Change takes less time. One of each starter-type can be chosen.
Pikachu: His moves are more anime-styled. His FS becomes the Volt Tackle from the Anime.
Pichu: B Move becomes Charm, which results in the opponent becoming "shieldstunned". Side B becomes Double-Edge which works like quick draw, but quicker and more powerful. Down B becomes Shock Wave, which results in nearby foes becoming entrapped in electricity. (Like Zapdos from Melee, but Pichu ends up with half of the damage of his opponents.) His FS is Volt Tackle from Brawl.
Mewtwo: His side B becomes Will-o-Wisp, a blue flame that homes in on nearby foes. His FS would be Pyschic, which causes nearby foes to shoot upwards.
Jigglypuff: Sing lasts twice as long. Side B becomes Protect (which negates knockback) when used on the ground, and Body Slam if used in the air.
Lucario: Side B becomes Bone Rush. With Close Combat becoming his New FS.
Kirby: Uses the powers available from the series. With "Neutral" having Inhale, Sliding Kick, Hi-Jump, and Plummet as his B, Side B, Up B and Down B respectively.
DeDeDe: Side B becomes Rex Wheelie, which would work like Wario's Bike. Jet Hammer becomes a spinning move instead of an uppercut. His FS would have Wheelies instead of Waddle Dees.
Meta-Knight: Uses standard moves that he actually had in the series. Final Cutter is his Neutral B move if used on the ground, otherwise it's Mach Tornado. His FS would be a giant tornado (like in KSSU)
Mr. Game & Watch: Oil Panic now requires 5 projectiles, but breaks shields and has no startup lag when filled.
Ice Climbers: If one of the climbers is KO'd, you gain control of whatever Climber is left, regardless of who it is.
Link: Has more air-time with his UpB
Young Link: Uses his masks.
Toon Link: Uses Skull Hammer for his Down B, and rides a Deku Leaf with his SideB.
Ganondorf: UpB is now Teleport, NeutralB is Shadow Ball, and Down B is a punch downwards that spikes and has mid-long-range.
Zelda/Shiek: Down B takes longer.
Ness: PSI Teleport is his new UpB. PK Rockin' is his FS.
Lucas: PK Sheildoff is his SideB, and PK Ground (which works like DK's headbutt) is his new DownB.
Captain Falcon: Falcon Punch is twice as powerful. His FS no longer has cinematics.
Samus: Falls slower, but can't "Bomb Jump".
ZSS: Down B, and Neutral B are switched.
Sonic: Caliber, his sword from Sonic & the Black Knight, becomes his DownB.
Snake: C4 can not be used as a recovery.
Pit: UpB can be used again after being hit out of it.
ROB: Can use more than one gyro at a time.
Fox: Lasers do more damage.
Falco: Uses an Arwing for his FS. Laser can be aimed downwards.
Wolf: Down B becomes replaced with a counter-type move involving his claws. His FS summons his Star Wolf fleet to bombard the stage.
Any comments on the changes?