There are a lot of obvious ideas here that mostly involve Normal, Ghost, Ice, and Psychic, and there's some unique combos that would also be really strong like Ice/Electric having absolutely insane STAB moves, Freeze immunity, and resistance to two of the best and most common attacking types while only being weak to a few types. We already made 2 Ice types or I'd send Ice/Ghost, so instead I'm gonna do...
Normal/Bug
For anyone who ever played Burgundy Version, remember Plucks? That guy was broken as shit just from having Swords Dance + STAB Hbeam with some actual bulk (and then it also got a good coverage movepool). Here I'm thinking more of a "the only Bug to ever get a real Bug STAB move" idea combined with having the busted Normal-type moves and the benefit of bonus coverage that many Normal-types get (Plucks initially had Thunder/Ice Punches and Earthquake, as well as Focus Punch, which uh... was quite the move in that mod). We can also give it Swords Dance if we want, but there's a lot of room to play with this by giving it different levels of coverage or a signature move or SD/Agility or what have you.