no balas, they get to big for you to keep them in a good group
red tails and rainbows get agressive towards each other when they are older
columbian sharks are brackish i believe and the rest of the fish you want are freshwater
the clown loaches need to have a group of 5 at least to be happy, and that would be to many for your size tank. they would be good for a little whilt, but you would need a tank at least twice the size to fit them when they get full grown.
silver dollars would be great for your tank- not real plants though... you could get a shoal of 6 and some other fish and that would do nicely for this tank
if you have angels, NO NEONS, you could have a trio of angels and some silver dollars, unless you want tetras, and in that case you could have a larger school of diamonds, red eyes, bleeding hearts (heavily planted tanks (fake or real) work best for bleeding hearts), black skirts, lemons, and a few others.
if you choose angels, dont put rainbow with them. i dont have much experience with silver dollars and rainbows, so i do not know what would happen. a large school of boes. rainbows would look really good in your tank, and since they stay at about 4", you could fit qutie a few in there, perhaps 10-15. you might want to consider some dianos to go with them if you choose bose. rainbows, like gaint or larger zebra dainos
a large school of neons or rummynozes would look cool, or some of each, but no angels with neons! i think that the rainbows might out compete them for food since the rainbowas are so fast.
a knife fish would be fine BY ITSELF.
as for bottom feeders, you could have a good sized shoal of corydoras, or a trio of flagtail catfish, but good luck finding them, for in my area, they are like trying to find a needle in a haystack