Question

When you use say iron defense is the boost permanent?

Answer 1

It is permanent until the battle ends, you switch out(unless you use baton pass), or your stats are lowered in the case of iron defense it would take two leers or one screech.

Answer 2

The boost is permanent until the battle ends, unless your Defense is lowered with something like Leer or Screech, or until the Pokemon that has been boosted switches out.

Answer 3

Yes, its permanent for the battle, unless it's lowered by your opponent.