I just thought of an incredible one, maybe not possible, it could be considered too close for copyright, but still amazing.
Mii Metal Bender.
This Mii fighter is inspired by Disneys Big Hero 6 villain,
Yokai, he uses the power of liquid metal combined with psycic power to fight.
Neutral B: Metal Burst
Flings a burst of metal out, charging for longer makes it more powerful and travel faster.
Side B: Wave
A pulsating wave of metal slows foward until it reaches the end of a platform or goes 75% the length of Final Destination, acts similarly to the Ice Climbers old Neutral B that shoots ice blocks.
Down B: Steel Floor
Stamps a foot on the ground, and a sheet of liquid metal spreads all over the ground in a radius around the Mii, and lingers there for a few seconds, other fighters are slowed down while moving in it, and jumps from the ground only go half as high, if used in the air, the Mii makes like Greninjas dair and falls down quickly, slamming feet into the ground and putting out an even bigger field of liquid.
Up B: Lift
Two streams of metal from the feet pushes the Mii, acts like the Up Bs of Pikachu and Greninja (one stream for each direction), when the stream has stopped propelling (the Mii either ends the move or changes direction for the second half of it) the metal is sucked into the Miis feet again, like a rubber band, being hit by this metal at any point has large knockback.
Neutral 2: Rapid Fire Steel
Similar to Foxes laser, rapid fire small chunks of metal.
Side 2: Metal Hammer
Coats hand in a large chunk of metal in the shape of a hammer, swings hammer down into the ground, with big shockwaves and lots of knockback.
Down 2: Pillar Squash
At each side, the Mii summons two pillars of metal, flat at the top, which rise up, and then curve towards each other, this crushes anyone who was above the pillars at the time, staying closed and doing damage continuously until the opponent breaks out or after a few seconds of this, and does lots of damage, though it has no KO power at all.
Up 2: Rising Metal
Summons a platform made of metal at the Miis feet, this platform rises upwards, trajectory can be altered, after a second or two of this, it starts to fall, horizontal movement can still be controlled while falling, this move is similar to DDDs jump.
Neutral 3: Pike
Charging move, bursts a long spike of metal out of fist, if you're hit, it will keep pushing you backwards until it's worn off, like a weak version of Samus final smash.
Side 3: Spring
Blasts in the aimed direction, using the metal as a spring propellor type thing, similar to Charizards side B.
Down 3: Dagger Drop
Jumps up and simultaneously flings multiple thin blade/beam things of metal in a downward arc.
Up 3: Falling Lift
Same as the default Up B, except the metal isn't sucked into the feet again, and instead falls downwards after being used, hurting anyone below and knocking them down.