Moves that deserve nerfs at the moment:
Limit Cross Slash needs to be more laggy to make up for its insane multihits and kill power. U-air could also use a nerf.
D-tilt should have more knockback growth so it can only combo into aerials from 100% upward. B-air could also use more end lag or less knockback, but isn't quite as big of a problem.
I could see cargo U-throw being nerfed
(decrease damage to 8.5% and increase knockback to compensate, so he doesn't do quite as much damage with his grab combos), but he would get plenty of buffs in other areas to compensate.
U-air is really quick, does tons of damage, combos into itself, and kills. Nerf damage of hit 2 and we'll be good.
U-smash could handle being laggier or weaker. Have you seen how ridiculous it is?
EDIT: Also, increase knockback of U-tilt and decrease damage of U-air, and make last hit of D-air hit earlier with no change in FAF (so it now connects reliably but has more end lag to compensate).
F-air should either have more startup or less knockback. Right now it's both a combo and kill move that does big damage.
B-throw is the best kill throw and yet hasn't been nerfed while others have. He would also get buffs to compensate this nerf.
U-air needs to have less KBG on Luma. Right now it's a move that can kill stupid early or connect to Rosa for huge damage on a frame 3 move. Also, Gravitational Pull should have slightly less range and more lag to make gimping a bit riskier.
True Shoryuken could use for a bit less power, but a height increase to compensate.
Vanish should have much more landing lag. It's already amazing for recovering and baiting air dodges, why does it need such little landing lag to make it even harder to punish? Bouncing Fish could also be a bit laggier.
Flip Kick should be a bit less powerful and travel a bit more slowly, as right now it greatly helps recovery and is a really quick and powerful finisher.