Normalize
Gen IVThis Pokémon's moves all act as if they were Normal-type. Moves that inflict typeless damage do so as usual. Moves of variable type, such as Hidden Power, are affected. They otherwise work as usual, however; Weather Ball, for example, is always forced to be Normal, but it still has doubled power and looks different during weather. As Thunder Wave is prevented by immunities, unlike most non-damaging moves, it does not affect Ghost-type Pokémon under the effect of this ability.
Normalize in Battle
Normalize converts all of the Pokemon's moves to Normal-type, introduced in Generation IV. Every attacking and status move the user performs is treated as Normal-type for the purposes of type effectiveness, STAB, and interactions. Moves that deal typeless damage are the only exception and function normally.
This conversion has significant mechanical implications. The Pokemon loses all super-effective coverage -- Normal-type is not super effective against anything and is completely walled by Ghost-types and resisted by Rock and Steel-types. Thunder Wave, which normally cannot affect Ground-types due to Electric immunity, instead cannot affect Ghost-types under Normalize. Variable-type moves like Hidden Power and Weather Ball are also forced to Normal-type, though Weather Ball retains its power boost and visual changes in weather. Starting in Generation VII, Normalize received a compensatory buff: all affected moves gain a 20% power boost (1.2x multiplier).
Normalize is found on only 2 Pokemon: Skitty and Delcatty. Despite the Generation VII buff, the ability is generally considered a hindrance in competitive play since it eliminates type coverage entirely. However, niche strategies exist -- notably, Normalize + Fake Out creates priority STAB, and the ability can be creatively exploited with Entrainment to give opponents Normal-type moves, stripping their coverage as well.