You can have them in a community tank, but it is one that is built and stocked around the Discus. Most fish you find can not tolerate the temps discus need long term, then there are other problems like some community fish just being too active. This can keep the Discus spooked to the point they won't eat.
Some good tank mates for Discus are (but not limited to) rummy nose tetras,cardinal tetras, a species of black water BN like L183, GBR, certain species of Corie's. There are others but all these fish will do fine in a discus community setup.