If we're talking balance patches:
Kirby:
— Make Up Throw actually a kill throw. Please.
Pit:
— Increase horizontal air speed so his aerials can actually do work.
Samus:
— Fix Charge Shot priority so it isn't stopped by much weaker moves. (Affects Dense Charge Shot custom)
— Make Charge Shot chargeable in the air. (Affects customs)
— Make default Missiles, both homing and Super, behave the same as the Mii Gunner Missile in all respects. The endlag changes should also affect customs.
— Increase jump height when being hit by your own Morph Bombs and decrease lag from morph bomb jumping. Also, increase horizontal mobility while in morph ball form, both when placing a Morph Bomb and when morph bomb jumping. (Affects customs)
— Increase damage, knockback, and blast radius of default Morph Bomb.
— Make jab combo properly. I get that she's supposed to be bad in close quarters, but please fix that.
— Increase ZAir's damage output. Also, give it more hitstun somehow, enough that auto-cancelled ZAir can true combo into a fully charged Charge Shot.
— Fix hitboxes and hurtboxes on things like NAir, DAir, FTilt, FSmash, etc.
— Make USmash, FAir, and UAir link properly.
— Increase knockback or decrease endlag on FTilt.
— Increase damage output on DTilt.
— Increase damage and knockback on BAir.
— Decrease endlag on grab, and use frame speed modifiers to make her hurtbox less extended during startup.
— Speed up her roll dodges.
— Global engine change: make all ZAirs use stale move mechanics.
Basically, if you're going to play with the idea of "Samus is good at range and Charge Shot is too good, so she needs to suck at melee", then give her actual ranged options. Charge Shot is great and all, but you can't play a ranged character with just one good projectile. For one thing, having a greater variety of options makes a character more fun, even if all of those options are just "poke with projectiles". For another, a character with only 1-2 usable moves is hit hard by Stale Move Negation. In Smash, if a character has only one good move, they're almost inherently terrible even if that one move is so good as to be almost broken. Why? Because by your 10th usage of that move, all uses of that move are doing about 0.53x their normal damage, which also affects their knockback accordingly.
Zelda:
— Make Phantom Slash charge-storeable. (Affects customs)
— Decrease delay between Din's Fire release and the actual detonation. Right now, it explodes way after it actually stops, making dodging it completely brain-dead no matter how good Zelda's placement is. Also, increase damage and knockback on the sourspot hit, and increase the size of the sweetspot slightly. (Affects customs)
— Decrease landing lag on NAir.
— Move sweetspot on FAir/BAir to her foot, along with moving the GFX to match. That both buffs the moves' effective range (since the sourspot hit is about as good as not having hit at all in terms of hitstun caused) and makes actually landing the sweetspots more intuitive for first-time Zelda players.
— Slightly decrease UAir startup.
— Decrease jab startup.
— Slightly decrease DTilt endlag.
— Increase DSmash range/knockback? Maybe?
— Slightly increase standing grab range.
— Global engine change: Remove sliding with teleport moves.
Ganondorf:
— Increase vertical height and horizontal mobility of Up Special. (Affects customs)
— Increase damage and knockback of Dark Dive grab. (Affects Dark Vault custom)
— Increase height gain during grab release of Dark Dive. (Affects Dark Vault custom)
— Greatly increase damage and knockback of the darkness hit at the top of Dark Dive, making it a kill move.
— Increase damage of Wizard's Foot (affects customs).
— Increase FSmash's range, giving it some disjoint, and increase the size of the darkness GFX to match.
— Add visible darkness effect to FAir, increasing its range.
— Add visible darkness effect to Jab, increasing its range.
— Slightly decrease Jab and DTilt startup.
— Increase grab range.
Mii Gunner:
— Improve Charge Blast's damage and knockback, and make it chargeable in the air.
Mii Swordfighter:
— Slightly increase startup on Chakram to prevent infinites.
Robin:
— Increase range on Dash Attack.
— Increase grab range.
EDIT:
Ness/Lucas:
— Make PK Fire dissipate normally when clanking with hitboxes that out-prioritize it, instead of going off. Basically, the same nerf the Mii Gunner's Grenade Launch got.