Retired Viking
Fish Connoisseur
One Angelfish alone is not a good thing for him or the other fish. I agree with @utahfish, I had a mated pair of angelfish in a 55 gallon tank without a mated pair you should have at least 5 or more and a much larger tank. I keep my soft water fish (tetras/cory) in a tank that I add RO water to so it helps soften the water. Your mollies and platys are hard water fish like my guppies which I keep in their own hard water tank. It is not healthy to have fish in the wrong type of water, in the long run it will shorten their lives and cause extra stress.