Personally, I would like the following:
Characters:
Captain Toad; he would have a low jump but would be fast and powerful, using a pickaxe to hit people and his flashlight to stun people.
Dixie Kong; I felt like she had a better chance than K Rool and Ridley, considering her most recent appearance in Tropical Freeze. Her movement would have been easy to do as well, in fact, I'm surprised she didn't get in.
Wonder Red; I really like the Wonderful 101 and I thought he would make an interesting character, with his neutral B being to summon heroes off screen to create a hand that would amplify his basic attacks. His other moves would be Unite Rocket for his Up B, Unite Guts for his Down B, and Unite Spring for his side B. The other Unite Morphs would be his custom moves (Sword and Claw for his Neutral B, Gun and Boomerang for his Side B, Whip and Naginata for his Up B and Bomb and Bowgun for his Down B). As you can tell this is one character I've thought about a lot.
Phoenix Wright; I've been watching playthroughs of a couple of his games recently and I thought he would be a funny character to play as. His B moves would be the different shouts that he uses, each having a different effect. His up B could also be the Steel Samurai balloon from the first game.
Mii Sorcerer; I really think that the Mii Fighter could have done with a class that's a mix of defensive and area-of-effect moves. It's also the only other Mii class I could think of.
Stages:
Link Between Worlds stage; I'm really surprised they didn't do this one. I don't know how they could have done it, but I'm sure it would have been cool.
A new Sonic stage; Something from Colours would be cool, especially for the remixes, but I wouldn't mind one based on City Escape, which would be a traveling stage where you start by going down the hill, where cars would be a hazard, then it stops in the skate park, where GUN mechs will attack, then you go down the second hill, where the Truck chases you, the buzzsaws on the Truck would come in from the background as hazards.
And that's all I can be bothered to think of for now.
