Friend Guard is an ability introduced in generation 5.
9 Pokémon can have this ability, such as Maushold, Clefairy, Jigglypuff, Cleffa and Igglybuff. For 8 of them it is the hidden ability, usually obtained from events, raids or breeding.
Official effect
Decreases all direct damage taken by friendly Pokémon to 0.75×.