MegaSnow for Pearls and Spirits reasoning earlier
^DurantDurant
Extremely powerful with an incredibly useful speed tier that made an impact since pretty much the beginning of RU to its ban. Specifically the speed tier allowed it to outspeed and beat Cobalion (Superpower) and Virizion, both of which have hovered around A / A+ / S rank their entire time in the tier. CB was an underrated monster than broke many balance cores (Crunch to beat Doublade rocked) while also acting as a fast Pokemon that was very hard for offense to switch into. CS was very fast and could revenge kill virtually anything, as well as having Baton Pass to pivot. Hone Claws was a horrifying set up sweeper that had a very good chance of cleaning thanks to Hone Claws patching up accuracy issues and Hustle meaning it could afford to not run LO and use Lum Berry instead. Also had a decent defensive typing (although terrible HP / SpD sucked) and could break past common answers with Thunder Fang if it wanted to, although to be fair it wasn't very optimal most of the time. Mega Aboma is a very good mon but I don't think it had as great of an impact over its entire time in the tier as Durant, although it was incredibly powerful as the meta progressed, especially once ORAS hit.