Beads Of Ruin
Lowers Special Defense of all Pokémon except itself.
Full effect
The power of the Pokémon’s ruinous beads lowers the Sp. Def stats of all Pokémon except itself.
In game description
The power of the Pokémon's ruinous beads lowers the Sp. Def stats of all Pokémon except itself.
Pokemon with Beads Of Ruin
Using Beads Of Ruin in Cobblemon
Abilities are passive and always active, so Beads Of Ruin costs you nothing to run. If it is marked hidden on a species above, expect it to be harder to obtain: servers differ in whether hidden abilities come from breeding, an Ability Patch, or events.
See the Pokedex for which abilities each species can have, and IVs, EVs and breeding for how to actually pass one down.