I'd like to see Samus' regular grab be quicker, since when you could lock onto a Grapple Point int MOM, the Grapple Beam extended and connected over a large distance almost instantly. That, and have the Grapple Beam retract quickly as well, instead of sitting out in the open like an idiot if she misses. I'd also like to see her Grapple Beam have kind of a constant stick to it, where if she misses when she initiates the grab, the Grapple Beam doesn't become useless immediately, if that makes any sense. I like to be able to grab the side of the stage like in Melee as well as the ledge, just throwing that out there. Changing her running grab into something like a Lethal Strike or an Overblast would be pretty cool, just not sure how that would work without causing 30% damage since it would involve shooting a charge shot at someone's face.
Another change I could see working is changing Samus' dodge roll from the slow morphball from Brawl to the sensemove dodge rolls. In Brawl, the dodge roll I-frames ended while she was still in the Morph Ball, let alone waiting to return to human form. Either make her dodge rolls the sensemove dodge rolls, or make the roll and transformation back to human form faster, or have the I-frames last longer, or hell, put all of them in.
This is just a nit pick, but I'd like to see her walking/running animations changed to something that looks less clunky. From what gameplay has been shown, Samus has all of the slowish and clunky walk animations from Brawl, which just looks weird in the slimmed down Other M suit. Something I noticed is that Samus' shoulder pads don't react to her movement, they just stay in the same general position when she attacks, resulting in a lot of clipping, which I hope gets fixed later on. Maybe Sakurai is going to change these later, but still, just looks weird to me. The Charge Shot sound effects sound like crap in the Developer Direct. The charge up and fring sounds sound SOOOO wimpy compared to all the other Smash games, especially Melee. The charging up sounds made it seem the the ground was shaking, and the firing noise was like an uber shotgun going off. Giving the charge shot a tad more power would be nice, make it scary again.
The only other thing I can think of is either changing Samus' Up Smash to something that actually works, or buff the hell out of the current Up Smash, I've only gotten three kills with that Up Smash in my entire life. Maybe give it a bigger hitbox, or give it a vacuum effect like for Pikachu's Down Smash, so the attack doesn't miss if someone gets hit, with it since the last hit is the one that counts like her Up Air, and I HATE when that happens. Last thing is her falling speed, for the regular fall, keep some of the floatyness since it is in several games, but make it, like, .3x-.5x faster so she isn't a complete sitting duck. When she activates her fast fall, give it s 2x-2.3x speed increase, as opposed to Brawl where she barely fell faster at all.