While Rash isn't the most ideal nature for a Typhlosion, it isn't bad at all.
The best nature for a Typhlosion would most likely be Modest which increases Sp. Atk and decrease it's Atk.
You also seem to be mistaken about what Typhlosion being Miscievous means. You can see what it means here.
In order to see what IVs your Typhlosion has you can go to one of the Stat Judges. You can find the locations of them here.
Edit: You can find plenty of good move set for Typhlosion here.