Wrap inflicts damage on the first turn then traps the opponent, causing them to lose 1/16 of their maximum HP after each turn, for 4-5 turns. If the user holds a Grip Claw then it is always 5 turns.
In Generations 1-4, Wrap has 85% accuracy. Its after-effects last for 2-5 turns instead of 4-5. In Generation 1, Wrap simply inflicts its base power damage for 2-5 turns. While in effect, the target is unable to attack.