Battle Armor(JPJapanese: カブトアーマーRomaji: Kabuto Armor) is a Pokémon ability introduced in the third generation. Shell Armor(JPJapanese: シェルアーマーRomaji: Sheru Āmā) is an ability introduced in the same generation with the same effect.
Battle Armor and Shell Armor prevents the opponent from landing a critical hit on the ability holder. This is true even if the move or the ability is supposed to guarantee critical hits
Samurott