hello i think i have a 100-200l tank and i put 1 oscar, 1 jewel, 4 different gouramis,,i sucker, 1 upside catfish and an unkown one seen in the photo in the right.
there's a big difference between a 100 and 200l tank!! well regardless of that, even if it's 200l it's still not big enough for an Oscar, even by itself, let alone with all those other fish you need to be looking closer to 350l if you wanna keep him. I wouldn't keep gourami's with him either, he'll probably eat them when he gets a bit bigger. 1 sucker... I assume you mean a plec, well it totally depends on what sort of plec weather it's suitable to go with the rest.
I think maybe if you loose the Oscar you could be OK as you are, depending on what sort of gourami's and plec you have.... I don't really know much about juwel cichlids to comment on they're compatibility.