Originally Posted by Fat NoUserName
I am thinking that, true we are not going to tier glitch mons, but what if we do an exception with Mew?
The way that glitch works, you can easily Growl the opponent that sets the species (traditionally, Slowpoke) six times to get your Pokémon at level 1, which lets you get a Pokémon with negative experience and, consequently, jump to 100 on leveling.
Ignoring any concerns founded on principle - every Pokémon obtained by that glitch has equal potential to be gamebreaking. A level 100 Beedrill at Misty is a gamebreaker. There's not meaningful tiering to do there.