i have 2 Oscars about 3", emperor pleco, and a green severum in my tank right now i was wondering if/what else i could put in with them. suggestions on what fish would b helpful.

how big is your tank?

its 120g 48x24x24

I would say you're probably at your limit. How big is your plec at the moment?

about 5"

okay, probably won't get much bigger. What type of filtration have you got?

2 rena xp3's and a hob filter thats for 100g or something don't quite remember.

Seems like you got some pretty decent filtration there. However, when the Oscars reach 11 inches, and your Severum 10 inches, you'll realize that you've got quite a lot of fish. I'm not saying that under no circumstances get more tank mates, I just think that rather than giving yourself more work, enjoy what you've got and give them plenty of room to move around in without bumping into each other all the time which is what will happen if you add too many fish.

I would leave it at that, you may find it difficult to keep your water good if you add more fish

i have to agree with the majority here and say that when mature your tank will be just about at its limit for fish. having said that i am a firm beleiver in lots of room for your fish and on the plus leaving your stock list as it is will make your maintenance easier to do.