Question

What is the perfect level to use a fire stone on my pansear on Pokemon white?

Comments

It depends on what you want

Answer 1

I would say either level 34 when it gets fire blast, or level 43 when it gets Crunch.
If you have a good amount of TM's, I would say evolve it whenever, since you should be able to teach it moves like Flamethrower, Shadow claw, Grass knot or Solarbeam.

So I would say...
If your pansear has higher special attack, level 34.
If your pansear has higher attack, level 43
OR if you have a bunch of TM's, evolve it whenever.

Hope I helped!