Spikes is a Ground-type move that sets the Spikes entry hazard on the opponent's side. Up to three layers of Spikes can be set. Flying-type Pokémon and Pokémon with Levitate are not affected by Spikes.
Spikes will do a varying percentage amount of damage to each Pokémon that switches in on that side depending on how many layers have been set:
Rapid Spin can remove the entry hazard from the user's side of the field, while Defog removes the entry hazard from both sides of the field.