Cresselia

Cresselia is a fantastic support Pokemon due to its access to a great signature move in Lunar Dance, which allows it to enable powerful offensive Pokemon that are otherwise dealt with by constant chip damage and status. Meanwhile, its enormous bulk allows it to check a multitude of threats such as Mega Medicham, Mega Diancie, and Mega Metagross. Despite these positive traits, Cresselia is held back by its Psychic typing, which leaves it vulnerable to commonly present Dark-types, such as Weavile, Bisharp, and Tyranitar, as well as Bug-types like Mega Scizor, Mega Heracross, and Volcarona. In addition to this, Cresselia's recovery is often hampered by the presence of sand from Tyranitar. Despite this, Cresselia still manages to play a key role in the tier due to its ability to tank a variety of hits as well as wall key threats such as the aforementioned Mega Medicham.