Just be warned, they DO NOT like each other. They will tolerate it, then one day one or the other will end up dead. Having it fine once is a fluke... Twice, can be asking for trouble. Betta fish come from the gourami family, and with a male gourami a colorful betta with longer fins poses a threat to his territory. And vice versa as well.
Also, for the platys get one more to even them out
If they are two males, you need one male. One female one male, then another female.
Same goes for the glolight tetra. Mainly because they are social, schooling fish, and these guys do best in 5+.
Your pleco will have the highest bioload
They may be cleaners... But they don't eat poop. Make sure to grab a water testing kit, and it will allow you to watch the levels of ammonia, nitrate, nitrite, and even pH.