I'll go through characters I am either pleased with or against (new ones that are not mentioned are ones I have no opinion with)
Dr. Mario: Melee fans are going to hate me, but I think he should be removed
Paper Mario: He is really the only other "Mario" that would be a great edition
Dixie Kong & King K Rool: Nice to see someone that isn't choosing between those two...
Cranky Kong: ...but I think 3 newcomers for the DK series is too much
Young Link: We have seen some nifty movesets for Young Link, but Toon Link is more-or-less his successor...
Toon Zelda: I don't think we need an even floater Zelda "clone"...
Tetra: But Tetra would be a nice way to add some unique additions from the "Toon" section
Lucina: Needs decloneing to be accepted
Pichu: I love the little buddy (favorite Pokemon), but we don't really need it back
Wolf: Never understood why he wasn't brought back as DLC, let alone removed in the first place
Dark Pit: Unless he gets significantly decloned, no
All Pikmin Characters (minus Olimar): Considering the series, Olimar is fine by his own. Alph
may work as an additional character, but look at my thoughs of clones
Elma: Need more Info (Don't know who this is)
Shantae: One of 2 Purple Haired Pipsqueaks I would love to use in Smash (where's Lilac?
)
Ice Climbers: Why you do this 3DS?
Inkling: Would be a nice "New" edition
All in all, I am pretty fine with this, though a total of 11 characters would be cut from me.