We may disagree, but science is against you on the angelfish. As you've asked, I will explain.
Having a group of angelfish with two, three or four fish is asking for trouble. This is a shoaling species, and a group will develop an hierarchy. The tank size factors into this obviously, and individual fish can always act outside the norm for the species. But it is always better to know the species behaviours and provide a natural setting rather than attempting to force the fish into what is for them a totally artificial setting. The stress this can cause usually means harassed fish which means dead fish with the dominant surviving. A group of five has been proven to avoid this problem, in most cases. There was a scientific study a couple years ago that determined fewer than five angelfish always (in the study) cause increased aggression in all the angelfish, leading to problems.
Now, I did mention the exception of a bonded pair previously. That is a very different thing. But the pair must accept each other and bond. The best way to achieve this is by letting them bond from within a group.
As for single angelfish, yes, that can work. But I am not an aquarist that recommends acting contrary to nature, and forcing a shoaling fish into this situation is not the best care. But it can work.
As for the sparkling gourami, if you can tell male/female from the group of immature fish in a store tank where they are obviously under stress to begin with, fine. But this is not at all easy. The group does work best with this species; adding more later is certainly not advisable. With a small group initially you get natural behaviours so they are more interesting, and they will be healthier. Providing what fish expect is always advisable, as Dr. Loiselle mentions in the green citation in my signature block.
I'm adding a link to a video demoinstrating the ideal angelfish aquarium because it provides what the fish "expect" as this is programmed into their DNA and we are not going to be successful going against it. You will notice their interactive behaviours; without a group this would end in dead fish.