The X Sp. Def (Japanese: スペシャルガードSpecial Guard) is a type of battle item introduced in Generation IV. It temporarily boosts a Pokémon's Special Defense stat.
At Join Avenue's Market, X Sp. Def can be bought in dozens at $3150 each, which equates to $262.5 per X Sp. Def.
Effect
Generations IV to VI
When used from the Bag during battle, it raises the Special Defense of a Pokémon currently in battle by 1 level. In Generation VI, it also increases the Pokémon's friendship a little.
Generation VII onward
When used from the Bag during battle, it raises the Special Defense of a Pokémon currently in battle by 2 levels. It also increases the Pokémon's friendship a little.
Wonder Launcher
The X Sp. Def appears as four Wonder Launcher items, increasing the Defense stat by 1, 2, 3 or 6 levels. It costs 3, 5, 7, or 11 points to use respectively.