"So lesson is fish need to be in pairs. Like species or not."
I don't think that was the lesson... the order of you fish could have been the simplest solution and, as Scooter said, "research and more research" is the lesson.
Research would show just how few are successful at keeping the Cleaner Wrasse alive and even fewer would suggest its purchase to solve your problem at the price of its life. As different as a Yellow Tang and a Royal Gramma are, it is likely that the aggression would've been short-lived without doing anything (although I would have rearranged some rock work or blacked out my tank if I saw too much aggression) and the YT not showing interest in the RG now could be as more about correlation than causation.
Please do some late homework on the wrasse.
I don't mean to come across as petty or condescending, but you came here for advice, got it, went the other way and claimed success in the span of 1 day.
Good Luck
Mike