Mew

Mew is an extremely dominant force in the LGPE OU metagame, excelling in almost every regard. Its 100 Speed tier lets it outpace a huge number of relevant Pokemon and sets the boundary for what is considered fast. Mew also has some of the best mixed bulk in the entire game, enough to avoid a reliable OHKO from any unboosted attack, while also being backed up by reliable recovery. As a result, it can effectively wall or at worst check a majority of the metagame with the right set. Its offenses are average by the metagame's standards but are enough to let it deal respectable damage both physically and specially. The Psychic typing is great, exploiting the low number of Pokemon that resist it greatly while also not having too many noteworthy weaknesses. Mew's movepool is possibly its most notorious feature, however; with amazing coverage options both physically and specially, great utility, and setup options that bolster its decent offenses as well as the aforementioned recovery Roost provides, Mew is extremely versatile and can run more viable sets than any other Pokemon by a large margin, excelling in most of the roles it assumes. Despite its numerous oppressive qualities, Mew does have significant weaknesses that keep it from being overwhelming. Most Mew sets are extremely vulnerable to being worn down by Toxic, and some faster Mega Evolutions such as Mega Beedrill and Mega Pinsir can dispatch of most sets easily after minimal prior damage. However, Mew can almost always get around these issues via team support or niche moveset options.