This is in my opinion:
1. Make her Homing Missile ACTUALLY home in on characters: This move is useless so far as it never works like you want it too. When it does home in on the character, they would have already dodged it. The Homing Missile should act as a disruptor to approaches, and it doesn't do that at all.
2. Increase the knockback of the sourspot in her dair: This move is very strong as a meteor, but the sourspot is a bit too weak, weaker than other sourspots like Ganon's and Falcon's sourspot. This move can be a very solid combo ender if the sourspot had a bit more knockback too it.
3. Usmash: This move needs to get the treatment Link's Usmash got: MAKE IT LINK. Samus' Usmash has been worthless in every iteration of Smash, and this is sadly no exception. I don't know why they can't get this thing to work right. Just increase the hitboxes on the blasts, is that so difficult?
4. Jab 1 needs IASA frames: In order to make this thing not suck, give it IASA frames. If the whole point of this move was to use it and switch over to another move, add IASA frames or add more IASA frames if it already has some to make it at the very least a safe jab. Samus contains probably the worst jab in the game and it needs buffing.
5. Increase the knockback of dtilt: Was always a kill move in the previous Smash games, not anymore, or at least not as good compared to the other ones. Even Brawl Samus had a stronger dtilt.
6. Increase the knockback of Dsmash: This thing can be one of Samus' best moves, but it's so freaking weak, it's one of her worst. In Melee and even in Brawl, Dsmash was one of her best moves. Why is this move so bad now? Increase the knockback of this thing guys.
7. Decrease start-up and end-lag on Grab. Seriously, Samus has a pretty solid dthrow that leads into combos. But try and make the grab far easier to, you know, GRAB with.
8. Hitbox increase on Fsmash explosion.