Blue gouramis and gold gouramis are the same species and you want to make sure you don't have 2 males if you want to have three of them. They are very sturdy, but the ventral fins ("feelers") might be too tempting for the barbs. The red-tailed shark would probably be OK; you definitely only want one as they are very aggressive to their own species. The bushy-nose pleco is one of the smaller types, so it should be OK. Red claw crabs aren't totally aquatic and they are highly specialized feeders. They will die. If you want a crustacean, a blue lobster might work (not sure if the pleco would be a problem with the lobster) They can go after fish sometimes, but the barbs are very fast and don't hang out on the bottom.
In lieu of the gouramis, you might consider giant danios, roseline sharks (denisoni barbs), or some of the larger tetras (such as red-eye Moenkhausia/glass tetras). I thought about silver dollars or bala sharks, but they get too big. You might consider a rugged type of killifish, Aplochelius lineatus. They're readily available currently as "Golden Wonder Killies". They are very sturdy, get to a good size and hang out at the water's surface. Again, you'd probably want one male and two females, although in a 70 gallon, you might be able to keep 2 trios.
In lieu of the gouramis, you might consider giant danios, roseline sharks (denisoni barbs), or some of the larger tetras (such as red-eye Moenkhausia/glass tetras). I thought about silver dollars or bala sharks, but they get too big. You might consider a rugged type of killifish, Aplochelius lineatus. They're readily available currently as "Golden Wonder Killies". They are very sturdy, get to a good size and hang out at the water's surface. Again, you'd probably want one male and two females, although in a 70 gallon, you might be able to keep 2 trios.
