I don't know anything about Discus except they have this slime/mucous and a lot of people keep them in bare bottom tanks and they need lots of water changes and maintenance.
Interesting fish IMO.. and no these can't be kept together, each needs to be individually researched.
Plecos (I love bristlenose plecos), loaches (khuli loaches are my newest faves), cory catfish, rainbow shark, ghost knife fish, freshwater eels, gouramis,.rams, angelfish.... I could go on and on.
Walk through the fish stores and write down what sparks your interstate, then research each species and when you have an idea we can help you with a stock list.