See it ending in you having just one pair, most likely the pink skunks.
I had a spawning pair about 5 years ago, the most aggressive pair of clowns I have every owned (( have been keeping clowns for 20 years now )), they even took out a golden dwarf angel.
I tried it with a pair of percs and tomatoes in a 180. Even with "host" corals on opposite sides of the tank it didn't work for long. I had to rehome the tomatoes.
I have 3 clowns right now, in my 125. A pair of Picassos and an Ocellaris, they get along great and all 3 are hosting my Pagoda, lol. I plan on adding another Ocellaris soon to see what happens. I introduced the Ocellaris as a baby which is why I think they got along and I plan on doing the same for the next, and hopefully so on.
I think it depends on how and when they are introduced. If you add them all at the same time you have the best chance of them getting along. But if you have an established pair and then add another fish you will have trouble. If you are going to add more clowns after an original pair I would re-do the aquascape first.
i'm with trex on this. i think 2 pair is a bad idea. i have seen exceptions, but the majority of the time it doesn't work...
on the other hand, i have introduced a single pink skunk in my tanks to show my ocellaris and percs how the nem hosting goes. works like a charm. the pink skunk stays in the nem for a couple days to a week, i take it out, and the ocellaris / percs dive right into the nems that is a single and not a pair though. it's also for a brief visti and lesson.