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.
In Pokémon Masters EX, X Sp. Defs can only be used by certain sync pairs who have them as an item move. In addition, a variant of X Sp. Def called X Sp. Def All can be used by certain sync pairs. Both of these item moves have 2 MP. An X Sp. Def only raises the user's Special Defense, while an X Sp. Def All raises the Special Defense of all allies. A full list of all sync pairs who can learn X Sp. Def or X Sp. Def All can be found here.
Another variant of X Sp. Def exists called X Sp. Def All +. This item move also has 2 MP, and it raises the Special Defense of all allies by 3 stat ranks. It is exclusively usable by Lillie & Prinplup in Victory Road.
X Sp. Def: Raises the user's Sp. Def by two stat ranks.X Sp. Def All: Raises the Sp. Def of all allied sync pairs by two stat ranks.X Sp. Def All +: Raises the Sp. Def of all allied sync pairs by three stat ranks.