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The wielder has an 11% chance of inducing sleep upon, 10% chance of poisoning, or 9% chance of paralyzing (30% chance to activate in total) a Pokemon that connects with a contact move. Effect Spore has a separate chance of activation on each hit of a contact multi-hit move, and can status a Pokemon multiple times if the first status is removed by the effect of Lum Berry or similar items. If a Pokemon falls asleep in the midst of a multi-hit attack, it will stop attacking (unless it is holding a Lum or Chesto Berry, in which case it will wake up and continue attacking). Effect Spore is prevented by Safeguard, but not by Substitute.
Effect Spore's random effects can be handy, but they can be undesirable on Pokemon that rely on selective status conditions to deal with opponents, primarily sleep. Unfortunately, that encompasses every Pokemon with Effect Spore out there. Use another ability if you can.
Found in Dream World