Arceus

Arceus is one of the most threatening and metagame-defining offensive Pokemon in the format while also having a solid support set as a secondary option. For the offensive set, strong priority makes it a dangerous cleaner in tandem with a boosting move in Swords Dance, and it also has super effective coverage for nearly every common Normal-resistant Pokemon and the Speed to beat out foes such as Mega Diancie. Arceus is also incredibly bulky for an offensive Pokemon, which allows it to check a number of threatening foes such Darkrai and Klefki in tandem with Lum Berry. Meanwhile, its support set stands out thanks to a lack of exploitable weaknesses and can be incredibly difficult to break through. Arceus also has a deep offensive and defensive movepool, and it is one of the few Pokemon that can be easily paired with itself to become even more threatening. However, it can be somewhat weak and walled by physically bulky Pokemon such as Giratina and Lugia. Arceus also has issues with how common Ghost-types are in the metagame.