Compound Eyes (ability)

Compound Eyes is an Ability Introduced in Generation III.

In battle
Compound Eyes increases the accuracy of moves used by the Pokémon with this Ability by multiplying the original accuracy by a factor of 1.3. This means that Thunder, for example, has 91% accuracy as opposed to the usual 70% (70 x 1.3 = 91%). A move with a theoretical accuracy of 77% or higher will have its accuracy set to 100% (77% x 1.3 = 100.1%).

Outside of battle
if a Pokémon with this Ability leads the party (even if fainted), the chances of finding a wild Pokémon holding an item increase from 50%/5% to 60%/20%.

Trivia

 * The only Pokémon with this ability is a mega, therefore its outside-of-battle effect cannot be used. It's description is also unknown, the one above is taken from Bulbapedia.