That's a pretty good idea!
I also had this idea about Assist Trophies. To have a certain character come out of an Assist Trophy, you must first have gotten the trophy in the lottery or in Single Player mode. Say, for Samurai Goroh to appear, you must first have gotten the Samurai Goroh trophy. (assuming the trophy stuff returns from SSBM)
I also thought up some movesets for some characters i'd like to see in the game.
Petey Piranha:
A moves: slaps with his leafs, maybe kicks
A smash up: Petey dues an upward headbutt (kinda like Pichu)
A smash down: Petey slams his head into the ground forward and back
A smash sideways: Petey headbutts the opponent (kinda like Bowser)
B: Sludge Spit: Petey spits sludge. The longer you charge this move, the stronger it gets and the further it goes
B side: Tornado Leaf: Petey does a pirouette and it sends a tornado across the stage (he had this move in Sunshine, when you fight him the second time)
B up: Fly: Petey uses his leafs to fly upwards
B down: Spike Plant: Petey plants his legs into the ground and spikes protrude from the ground at both his sides, knocking enemies away
Final Smash: Huge Inhale: Petey inhales all enemies on the stage (doesn't matter where they are), and spits them back out with enormous force
Entrance: A flower bursts out of the ground and Petey steps out of it (like in Mario Strikers Charged, his Megastrike)
Taunt: Petey claps his leafs and mumbles something
Waluigi:
A moves: punches and kicks
A smash up: Uppercut: Waluigi slams his fist upwards
A smash down: Split Kick: Waluigi goes into a split and kicks forward and back
A smash sideways: Waluigi Fist: Waluigi delivers a hard punch
B: Goo Spray: Waluigi takes out a small potted Piranha Plant that spits goo
B side: Rose Whip: Waluigi takes out his Rose Whip and strikes opponents with it (kinda like Sheik, Rose Whip comes from Mario Strikers Charged)
B up: Waluigi Pirouette: Waluigi does a pirouette which makes him fly upwards (from Mario Power Tennis)
B down: Bob-Omb Throw: Waluigi plucks a Bob-Omb out of the ground and throws it (kinda like Peach)
Final Smash: Bob-Omb Machine: The Bob-Omb-shooting machine from the Mario Power Tennis intro appears, and Waluigi shoots Bob-Ombs all over the stage
Entrance: Waluigi appears out of a warp pipe
Taunt: The cross chop thing from both Mario Strikers games
Krystal
A moves: strikes with the staff, maybe punches and kicks
A smash up: Staff Stab: Krystal stabs the staff upwards in a stabbing motion
A smash down: Staff Sweep: Krystal kneels and sweeps the staff across the floor, hitting both forward and back
A smash sideways: Staff Strike: Krystal strikes the opponents with her staff (kinda like Ness)
B: Fire Blaster: Krystal fires the Fire Blaster from her staff. The longer you charge it, the stronger it gets (kinda like Samus)
B side: Ice Blaster: Krystal fires a freezing ray from her staff
B up: Rocket Booster: Krystal uses her staff's Rocket Booster to fly upwards
B down: Ground Quake: Krystal uses the staff to create small earthquakes (kinda like DK)
Final Smash: Super Ground Quake: Krystal uses the staff to create huge earthquakes
Entrance: She comes flying in on a CloudRunner
Taunt: The shielding motion from Star Fox Adventures, when you pressed the R button
Lucario
A moves: punches and kicks
A smash up: Bone Rush: Lucario takes out a bone and wildly strikes it upward
A smash down: Iron Tail: Lucario sweeps opponents off their feet with his tail
A smash sideways: Giga Impact: Lucario smashes the opponent away much stronger than opponent's smash moves, but Lucario becomes immobilized for a short period of time after smashing
B: Drain Punch: Lucario charges his fist for a while, and when it is fully charged, he can walk around and strike a foe with it. It then also heals Lucario a bit.
B side: Aura Sphere: Lucario fires a sphere which is controllable with the control stick (like Ness)
B up: Sky Uppercut: Lucario uppercuts, and also goes upwards at the same time
B down: Me First: Lucario waits for the foe to attack, then blocks the blow and uses the foe's move, but stronger (kinda like Marth & Roy)
Final Smash: Hyper Beam: Lucario fires off a powerful Hyper Beam, during which Lucario stands at one position, but can aim the beam upwards or downwards using the control stick
Entrance: Lucario comes out of a Poke Ball
Taunt: Lucario looks into the sky
