Raises the power of the user's Bug-type attacks by 1.5x while the user has 1/3 or less of its maximum HP (rounded down). Out of battle: If the user is your lead Pokémon, the encounter rate for wild Pokémon is increased.
Hidden Power's power and type vary depending on the individual Pokemon using it, ranging between 30 and 70 power. There is no way to change a Pokemon's Hidden Power type or power, so you are stuck with what you have. Hidden Power is always a Special-based move.