Quick Feet raises the ability-bearer's Speed by 50% when inflicted by a major status ailment (poison, burn, paralysis, freeze, or sleep). If paralyzed, the Pokémon does not suffer the usual drop in Speed.
All other effects of the status condition remain, such as losing HP each turn (poison, burn) or being unable to attack (paralysis, freeze, sleep).
If a Pokémon with Quick Feet is the leading party Pokémon, wild Pokémon are only half as likely to appear.