There shouldn't be a reason that those 2 wouldn't make a pair, assuming they weren't both females.
Generally it goes from unsexed juvenile, to male to female --- the end. Once female it will stay female*. A male will stay male if there is a dominant female.
* there was a report by Rod (( of Rod's food/Onyx )) of a Clarkii complex female reverting to male, but that is the only time I have heard of any clownfish reverting.