2 of 3 fixed header formatting

#There is no official Skeleton-like race for players.

If it's just for appearance and role-play purposes, you could suggest that he picks an existing race and be an undead/skeleton version of that. To keep it RAW you could state that all stats are exactly the same as the original race.

But if he wanted to play a skeleton because of any potential racial bonuses or traits, you will have to homebrew this.