"It's a shame that all this time I thought Metagross was actually good, only to be proven wrong by that article on Stuff You Should Not Be Using
It'd be really interesting if Metagross actually drop to UU."
That article is only a matter of opinion. Scrafty is still usable in OU, Metagross is not so bad, Claydol is actually good in UU, and speaking of honorable mentions, Whimsicott is amazing, Azumarill is great especially under rain, Hitmontop is a great spinner even in OU, and Virizion is great against rain teams except Tornadus-T. Electivire is not very good, but in lower tiers it can be a monster, and it's also a monster when you Baton Pass Shell Smash to him.
Obviously you are not going to use stuff like Charizard in Ubers, when you can use Reshiram or Ho-Oh instead.