though your tank is huge (which I'm jealous of by the way haha)....I don't think you could acclimate all those fish at once and your system handle the bioload unless you have an already cycled tank, cycled media, old decor/substrate that has good bacteria on it, and bio booster....unless you want to risk the fish or a huge bacteria bloom which can cloud your water.
I don't know much about sharks except that balas can get pretty big. Also you are having a lot of aggresion in your tank....are you sure you just don't want cichlids at this point haha.
I think if you got younger/juvenile angels then it might help them get use to the other members of your tank....just make sure you add them near the end. Angels also like planted tanks which will also allow line of sight breaks between them which will help them coexist not only with eachother but with other fish as well.
As for your bettas, make sure you tank has plenty of areas for them to hide/not see eachother. even with six females in such a large tank....some will chase them around until they can't see them anymore. Plants will help with this too. This being said....betta sororities are risky because individual bettas will have different personalities. I've been doing a lot of research on them (granted this is on a smaller scale than a 90 gallon tank haha, but it is also species exclusive) which you should probably do too. Larger numbers will help spread out aggression but only if the tank is large enough and there are enough separate territories for them. Odd numbers are also recommended. i think you might have more luck with overall aggression if you have 7 or 9 but you also raise your risk of getting one or more random females that don't like being in a sorority at all...let alone a huge community tank.
if you are talking about albino versions of the common/normal plecos....those things can get huge.....are well known to start becoming aggressive and sucking the slimecoat off of fish....and sometimes stop eating algae and the only thing they contribute to your tank is becoming poop machines.
I think you should definitely do at last one tight schooling fish like tetras. though they might become food for other fish. Having such a big tank really offers you the ability to highlight not only big showpiece fish but allows you to highlight schooling fish as well. That being said....you don't have any bottom dwellers....I suggest like at least ten of one species of corydoras. They school together, keep the substrate clean (but make sure you have sand substrate if you have them), and are just interesting to watch. Another really interesting fish is a kuhli loach (I LOVE THEM) they are like little drunken eels...but you will also need a sand substrate if you want to keep them.
if you like aggressive fish you could try maybe german blue rams....though they are known to not acclimate well to new tanks....they are aggressive and bottom dwellers.
