Is a Defogger necessary?

[SSJ2]

I took mine out, but Stealth Rocks are nailing my Volcarona by 49%. Is a Defogger needed?

 

[Uchiha]

For teams that have 4x weakness to rocks they're pretty much needed. It sucks because defoggers tend to be offensively impaired. Exceptions being excadrill (spinner) and LatiOs

 

[SSJ2]

What about Omastar?

 

[Event Horizon]

Pretty much what Itachi said. Pokémon with 4x weakness will get absolutely fucked over if you can't get rid of it, and it basically puts you at a huge disadvantage because you can't safely switch out without taking massive damage.

I pretty much almost always carry a Pokémon who can get rid of it or prevent one from setting them up (spinner, defog, taunt). The latter requires some prediction though.

 

[Six Trails]

What about Omastar?

It can't learn Defog or Rapid Spin.

 

[Doctor Havoc]

Donphan is another good option
Can just google which pokemon can learn
Defog/rapid spin/ taunt and stuff