That's quite vague. You say Uber is standard, but it isn't used as much as OU. You say it RU isn't standard but isn't used as much as OU. What defines a standard metagame?
I already told you, Any tier that's approved by Smogon experts based on usage. If more people play UU as much as OU for example, it becomes a standard metagame. But if one tier is not being used as often as Ou, then it's not part of the standard metagame.