Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Gold Barbs: Cool water fish, but not nippy.
Endlers: Angels can eat the adult sized males for sure, and probably all but the very largest of females. Certainly Angels with any sort of predatory tendencies will eat Endler babies.
Betta (female) probably a good tank mate for Angels. Highly likely they will be just fine together, mostly staying out of each others' way.
Dwarf Gouramis: Between Angels and Gouramis, I can see possible problems, but I am more worried about Gouramis having problems with each other. Gouramis are highly territorial, and may start attacking each other. There are a few Dwarf Gouramis that are so aggressive they do not tolerate any tank mates of any species. Also, Gouramis and (male) Bettas should not be kept in the same tank. Both species are territorial and will defend their territory from each other. Most female Bettas are not so aggressive, not territorial, so if yours is tytpical, then should not be a problem. If your female Betta is at the higher end of the aggression level, then she might attack the Gouramis.
In a larger tank (over 4' long) with lots of plants, driftwood or other surface markers, the Gouramis might be able to stake out a territory and stay out of each others' way, but I would watch that sort of set up VERY carefully, and be ready to move a problem fish to a separate tank.