72, Compatibility Q and looking for input

The Siamese Algae Eaters and Rainbow Shark might be a problem. Black/Rainbow/Red Tailed Sharks are very territorial, and may attack any fish that is shaped even remotely like them. The fact that you're planning on getting 4 or 5 SAEs may help in that the shark won't be chasing one all of the time, but if you don't want any fish being chased around your tank, stay away from either the SAEs or Rainbow Shark. Your angels should be fine, as the generally accepted rule with them is just one, or more than three. I don't really know much about rosy barbs, but if they're nippy you might want to avoid them with angels. If you want something redish colored, you could maybe do cherry barbs. I don't think they get as big as the rosy barbs, and the five I have are very peaceful. They are a fish that likes to hang out with it's own kind, but don't really school together, and therefore don't have the pecking order that causes nippiness in tiger barbs. I don't think that the faster moving fish are going to stress the angels, as long as they don't run into them or try to bite them or anything like that. They may actually serve as dither fish and make the angels feel more secure in displaying themselves.

Question about Rainbow Sharks

I was wondering what kind of fish I could put with my rainbow shark he's really small, I have a lot of plants and hiding spots for him, I just wanted 2 more bright colored fish to go along with him. My tank is only 2.5 gallons, if anyone knows anything I would really appreciate it.

If your tank is 2.5 gallons, it's nowhere near big enough for the shark. I'd say take him back to the store and get something that can actually live in a 2.5 (which limits you to a betta, and not much else).