Well, the Gouramis won't work with a Betta. The only Gouramis I've found ever work with Bettas are Croaking Gouramis, and they only work with female Bettas. I have a pair of them with 6 of my female Bettas, and everyone gets along fine.
Cardinal Tetras may or may not work. It depends on the Betta, and it also depends on whether or not they're fin nippers like Neon Tetras, which are a very poor idea with Bettas, since they reduce fins to little nubs with all their bites.
Swordtails are a possibility, but it depends on the Betta. Some are more threatened by bright-colored fish than others.
If you'd like my recommendation for tank mates....
6+ White Cloud Mountain Minnows
2+ African Dwarf Frogs
Assuming you have a 20 gallon or more, a school (6 or more) of Zebra or Leopard Danios, or even a mixed school of Zebra and Leopard Danios, since they mix very well together. They do need a fairly long tank, though, to have enough swimming space, and can be slightly aggressive when not kept in large enough schools of their own.
Those are just a few ideas. There are prohibitions, such as no Guppies, no Neon Tetras, no other Bettas (female or otherwise), no Tiger Barbs, no bright-colored fish of similar shape to a Betta, and no potential fin nippers. Bettas are easy targets for fin nippers, and they have a tendency to challenge and want to fight with bright-colored fish that look similar to them.