Don't think keeping male and female Betta splendens together long term is going to work. There's also aggression level that you have to consider. Some males and females can be aggressive to just about any fish, regardless of what they are. You can consider keeping larger species of wilds together, as for the most part, they are fine together. However, keep in mind that the endlers and tetras may get eaten if you decide to keep a pair of the large species. I have kept male and female mouthrooding species without too many issues and only remove the female whenever the male is holding.