Glalie

Mega Glalie gains an amazing ability in Refrigerate and high offensive stats when it Mega Evolves, becoming a potent wallbreaker that's able to destroy defensive cores, as well as a great Speed tier, allowing it to outspeed the likes of Meloetta and Sigilyph. Mega Glalie also offers utility with Spikes, which means that it even if it may be walled, it will not be useless. Furthermore, Mega Glalie has access to a very important priority move in Ice Shard, which allows it to revenge kill many important threats in RU such as Flygon and Virizion. Unfortunately, Mega Glalie's horrid defensive typing and average defensive stats leave it weak to common Fire- and Steel-types such as Emboar and Escavalier. In addition, Mega Glalie is extremely easy to wear down due to its vulnerability to entry hazards and the recoil damage that it inflicts on itself with Double-Edge. Mega Glalie's mediocre Speed tier before it Mega Evolves also means that it has a very difficult time switching in safely.