Raises the power of the user's Physical-based attacks by 1.5x, but lowers the Accuracy of the user's Physical-based attacks to 80% of their usual accuracy. Out of battle: If the user is your lead Pokémon, Pokémon with higher levels in an area have their encounter rate raised by 50%.
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.