Go scientist for the simray and you can use it to do things like freeze people, force them to wear terrible outfits, or randomly transform their furniture. You also get a satellite dish that can force people into angry moods and you can make serums to give people that can cause ill effects.
You can buy (from the computer) or fish up a voodoo doll and bind it to a sim and have it do bad things to them.
If you have seasons you can buy the weather machine. If you have City Living move to an apartment next to a festival lot and force it to snow or thunderstorm when there is a lot of people outside.
You can turn into an alien or vampire and they have abilities that can cause ill effects.
There is also a lot of mods that can do some pretty extreme things.
Then there is always building a dungeon basement to trap sims in. If you advance through the cop career you get cages and stuff you can use on your lot. Maybe some of the item unlocks from the doctor career could be good for doing things to sims (idk I never played a doctor)
Oh boy... that’s a lot of evil ideas I had there. Funny thing is I never even play an evil or mischievous sim. I always play super nice sims.