If the angels pair then they'll have issues with the rams and the kribs, they could easily kill them. Variety is nice but nothing really beats a large shoal of fish, I'd push for at least 30 of your chosen tetra/rasbora in this aquarium. That being said, if you want to have smaller schools with different species then there's no reason you can't have 15 harlequins then 10 of each of your phantoms.