Gouramis shouldn't be kept with Bettas, and neither should Angels. All are semi-aggressive fish, and will more than likely tear into each other eventually.
I do have a pair of Croaking Gouramis in with about 6 (I've lost count, as I keep changing it) female Bettas, but my male Bettas posture and flare at the Croaking Gouramis. The female Bettas just treat them like other female Bettas, but they are unusually gentle girls, so results may vary.
Personally, though, I would never put a male Betta in with any Gourami or Angel, or any Angel in with any Betta, male or female. As for Gouramis, it seriously depends on which species, as some are more aggressive than others. My Croakers are completely mild critters.