Technically speaking, Betta are not community fish. A male should be housed on its own in an appropriate tank, with no other fish. Shrimp may or may not be eaten.
While it is true that some may have success (though this is not always long-term) with other fish combined with a male Betta, it is a risk and this is not fair to the fish. I have not "tried" this with Endlers, but given that guppies tend to inflame most Bettas and nip them, and many Betta will try to eat guppies, I would not attempt Endlers.
Experiments may be less risky if you have tanks running to deal with separation should it be necessary. But this is still a risk and the fish deserve better from us.
Byron.