I don't know who should be cut and who should be kept, really. What we want isn't necessarily going to happen, but...here's a good list of opinions (now that is the keyword, isn't it)
Chop/Axe/Cut/Decapitate/Whatever
Any Link besides Link
Pichu and Mewtwo (isn't one pokemon enough?)
Roy (again with the one character thing)
Doc, only if the new costume keeps the pill as a projectile and the skull punch
Mr. Game and Watch, only to put in a new interesting character, or keep him
Cut people who are similar from the same game, get new games involved, because the
Nintendo systems have had a lot of good games to take from.
People to Change
Falco's moveset, maybe to counter fox???
Kirby, Bring the pink back into the house
Luigi's running A, just because of the annoying noise, or change the noise
Make Pika a little heavier, along with Peach
I don't know what to do with bowser, he has never been really used widespread, but he's
critical to the game, so i don't know.
Gannon. Complete redo, uniform and noises too
Do something so fox and sheik don't dominate so bad, but are still really good cuz i use
them, haha
Ness, for the better, but not as good as he was in the N64 version
Things to keep the same
Character themed stages with their own special music, but much expanded
Jiggles, cuz that pink puff ball kills me all the time right now
Ice Climbers, cuz they are really good already
Most of the rest of the characters
(off topic, sorry) the items, especially Mr saturn and mr freezie
I don't know, i know our opinions might not mount to a whole lot, but it would be really cool to see Nintendo come to smashboards to see what peoples opinions were