I agree with others that said 1 angel will be fine. I like pearl gouramis a lot, but they're very iffy with angels. If you decide to get 3 go with 1 male & 2 females. They're pretty easy to sex, males have longer dorsal & anal fins & colorful "chests" when big enough.
I prefer rasboras to many tetras. Tetras have teeth in the front of their mouths, rasboras don't so can't nip. Harlequin, espei & redtailed rasboras are all pretty & are easy to find. If you go with tetras I kept lemons with angels but their coloring is rather subtle. No to serpae, skirts & long angel/gourami fins. You might get away with cardinal tetras or rummy noses but not neons & an adult angel, that 1/4-1/2 inch difference in tetra size is key.
I would start with either gouramis or rasboras/tetras then the other. Get a small angel eventually so the others have time to grow. Then maybe corys or pleco.
I love all corys! Get at least 6 or 8 of the same species. If you go with dwarfs (dwarves?) you can have even more! Pygmys don't even count much as bottom fish, more low to midwater swimmers.
For plecos, BN ancistrus are readily available & come in several varieties. Males tend to hide but females are out & about. Chose a smaller fish if you're hoping for a female. Some of the other small plecos hide all the time & some are nocturnal too. I like clown plecos but they're nocturnal day hiders, perfect for insomniacs like me, lol. Provide at least 1 hiding spot under rocks or wood for any pleco, some like wood, others need it.