This character is very unfun to play against; at minimum, make this character a combo doll so that when you do get in on him, he isn’t just tanking you into dtilt or getting a FH grab into a tech chase started. Melee link could do some tilting dhit, but he was at least easily combo’d by the entire cast. We don’t need to make an ultimate character; none of us came hear to play ultimate.
I’m not against zoners in the game, but this character feels tailor made to suck the fun out of the game and make the other player miserable. I’m not convinced the Slade players are having fun either; his recovery is god awful and not dynamic to edgeguard.
I don’t know what to suggest because I’ve never liked playing as or against this archetype at all, but please god don’t leave this character like this. When the Slades finally get good at the game, we’ll all be miserable. Like, god forbid someone like Aklo take an interest in really pushing the character and make everyone hate their lives.

I have said for a while that I think they made Slade too complicated, and therefore too hard to balance. The core issue is the permanent purchasable upgrades. Base Slade has to be bad so the upgrades can make him good.
Here’s how I would change Slade:
With this, Slade generally wants to be holding drop of nourishment even while fighting, until he wants boomerang or bomb for a kill setup. There would need to be some balancing/tweaking to the rest of his kit to bring things in line, but i think this would be more true to his core character as well as more fun to play as and against.

Can you use zair while holding an item or would you just z-drop the item