Answer 1

Sort of. When you're battling in a tier, you have to use Pokemon from that tier, and below.
You can't use Pokemon that are higher.

Ex: If your team has Dragonite, then it's an OU team. However, you can still use Pokemon from UU, RU, NU, etc.

Pretty much yes.

Comments

Ok I'll have to see what pokemon are in each tier :P