DwarfCichlidLvr
Fish Addict
well pandas are one of the smaller non-pygmy cories. They are also less shy.For the cories you probably want to consider one for the dwarf species rather than Pandas. Its risky either way but an option would be to get the cories a few weeks before the betta. If you do it the other way around he may regard the tank as his territory and added fish may be seen as intruders.
IMO either would work out well. Just be warned with pygmys though (of either species). They are one of the shyest fish i know of. Just ask @NCaquatics. So just be sure to get 12-15 pygmys.
On second thought, just get the pygmys. Pandas like cooler water than the 79 bettas do best in.
I do agree with adding them first though.