Ok, first of, , **Starmie is only UU by Smogon standards**. There are other tiers , but they aren't as big and I don't know where these place Starmie. Since Smogon tiers isn't enforced by Nintendo, GameFreak or the games themselves, **Starmie isn't officially in any tier, since there are no official tiers.**
Smogon base their tiers on usage, and since people aren't using it anymore, it have dropped in tier as well.
So asking wherever something is in a certain tier by Smogon standards but "not caring about Smogon" is redundant. If you don't care about Smogon tiers, don't worry, you don't have to play by their rules, since they are unofficial.