At first I was like 'wait, what, multiple Meloettas? Aren't legendaries supposed to be unique?', leading to some research about multiple legendary Pokémon.
Today I learned there is actually a difference between mythical and legendary Pokémon and that there is indeed evidence some legendary Pokémon are not alone. 
So, how do we do this for our RP? What Legendary or mythical Pokémon can exist in multitudes and which ones don't?
Arceus is obviously unique. The Creation Trio and Lake Trio are also unique, as is Mew. But the others?


Long story short though: Sure, I'd love to play Meloetta :)