Baby Got Back ; similar to HW turning you into a snail, except is a long-medium range (must be in user's viewing distance) stand that makes specific opponent gain fat and increase cholesterol at alarming rate. Eventually, if not defeated, opponent will explode from rapid increase in size, deteriorating health, etc.
Bad Reputation ; Uses telepathy/mind control on mass amounts of people in the area and turns them into extreme negative and (sometimes)deadly violent maniacs, can also direct this anger towards specific opponent. Most useful against people like Jotaro who wouldn't want to harm innocent people. - cons : because it functions by telepathy, puts mental strain on user/requires a very very mentally strong and intelligent user, similar to scary monsters, enough outside focus on a particular subject can decrease the stand's effect (example : stand is being used in new york city, but somehow all of the billboards/screens change to idk a tap dance video, people stop focusing on enemy & effect wears off)
This Will Be (An Ever Lasting Love) : meshes user with items/elements and allows them to turn them into stand objects as opposed to real life things? think of it like a direct rip-off of kevin's power from ben 10, except everything the power is directed at is transformed from a real life object to a spiritual(?) object, meaning that you can now shoot your oppenent's stand, stab it, etc. user can also wear stand in elemental form as a stand-suit. - con : once turned into spiritual object, said object cannot be turned back into real item, stand-suit doesn't fair too well against actual stands? idk this idea was a bit hard to decide on whether to make it too OP by "the entire stand is kevin from ben 10 and it works on both stands and users" or to limit it like above
Not really main antag worthy, but I had two more ideas:
Feeling Good : Transforms a large surrounding space (meaning all short range stands are going to have a bad time) that put's opponents into very depressed state, emotionally damaging opponents, can bring opponents to brink of killing themselves - cons : because user cannot control who gets affected, user himself is constantly haunted by all the loved and innocent people they accidentally hurt, is very depressed
Isn't She Lovely : Creates a "bait" (like beach boy) that makes opponent SEE everything in that colour/only in relating colours (for example, bait is a red stool. User now only see's what is red/hints of red) or they could see everything EXCEPT that colour? Or they could see EVERYTHING in that colour? idk haha