I have a Male German blue ram. He is great with my syno petricola's (small catfish), bristlenose pleco's, forktails rainbows. I had a dwarf gourami and they did not get along. The Gourami beat him up all the time, the fish store said it's usually the other way around so that is a bad combo. But all the other fish got along great. Since the Betta is a Labrynth fish like the gourami you might have issues with them. Most betta's stay on top and rams stay on bottom but my gourami went to the bottom to chase the ram. So it's hard to say, it's a gamble with a betta but you might be fine.
One thing I would suggest if your looking at the fish store for one is to observe the fish's color. small juvenile rams should not be super colorful. If they are extremely colorful but small they are probably hormone injected which are very common lately. They typically die in a week after getting them. Try to get a non hormone injected one which you can tell by the coloring. They might have some blue and yellow in them but nothing like what you see in pictures until they get past that juvenile stage.
Good luck, and if you do get them do me a favor and send me a PM after about a month as I have a betta I was thinking about putting in my tank but I don't want issues with the ram and him.
:
