Ok, after further experimentation with NDenizen's set, I can safely conclude it's pretty freaking awesome.
Although I admit 1277 is a very modest rating right now, it's a really cool set and works just how I want it to.
If it has rain support and copies a Nattorei or a Doryuuzu, few opponents initially realize how freaking resilient it is. In fact, it walls Nattorei (you have to let something die to keep it away from gyro ball though) and Doryuuzu (bar the rare Brick Break>Xscissor, Return, Rapid Spin ones) and is really hilarious. Terakion is an issue but only if you're in SS. If you copy any typing then get a +1 from CM, it's as good as dead in rain to what is effectively double STAB surf. Also avoid Superpower Scarftar; if you copied a Nattorei, it will kill you.
tl;dr Mirror Type Latias is really cool actually
Latias (F) @ Leftovers
Trait: Levitate
EVs: 252 HP / 4 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Mirror Type
- Dragon Pulse
- Surf
- Calm Mind
Use with rain support and kill t-tar and the odd hippo early on, win
I've got to try that set, seeing as you crushed me with it.
How much does it miss Recover?
It also seems to break stall really well, seeing as if you've copied Nattorei or Forretress you're immune to Toxic as well as Leech Seed in Nattorei's case.