oops just realised u said any tank ok well,
yes, mostly everthing you got down is compatible in your 30 except the gourami will proabaly not get on with the betta, so I wouldn't put a gourami in. No common pleco, they get REALLY big, but i dont see why you can't have another sort of pleco (just make sure you reasearch before you buy). I think some cory cats would do well in your 5g with your betta but some species get big, albino and pandas stay fairly small.
German blue rams require good water quality, so if your willing to do frequent w/c then you'll be ok.
Mollies, swordtails, guppies, danios should be fine with your current stocking. But i don't mean all of these fish, just pick your favs and go from there