Aerodactyl

Aerodactyl is arguably the best Mega Evolution in UU, as it is easy to fit onto most teams due to its high customizability and expansive movepool, decent bulk when invested, and ability to set up, which can surprise the opponent. Specifically, Hone Claws can let it become a very potent wallbreaker coupled with the fact that its Flying-type STAB moves and some coverage moves are boosted by Tough Claws. Aerodactyl is also the fastest lead in UU, meaning it can shut down other leads through Taunt fairly easily, giving the team entry hazards without the foe setting up their own. Its amazing Speed tier before Mega Evolving becomes even better after Mega Evolving, outspeeding the entire unboosted tier as well as base 80 Speed Choice Scarf users such as Chandelure and below. Mega Aerodactyl is great at revenge killing as well, as its Speed and power make it an extremely reliable blanket check to most offensive threats such as Mega Beedrill, Shaymin, and Entei. While Aerodactyl has a lot of good things going for it, it struggles with bulky Water- and Steel-types such as Suicune, Mega Blastoise, Swampert, Forretress, Mega Aggron, and Doublade. It also has very common weaknesses in Water, Ice, and Rock, limiting the number of times it can switch in, as it is weak to Stealth Rock and Water- and Ice-type attacks litter the tier.