Ditto copies all of its foe's stats except for HP; thus, 252 HP EVs are used to maximize Ditto's bulk. Since Ditto copies the majority of its foe's stats, its IVs are only relevant in three cases: determining its HP stat, determining its Hidden Power type, and in the rare mirror matchup. In a mirror matchup between two Ditto, the faster Ditto will Transform first and be left with 5 PP. A Pokemon cannot Transform into an already Transformed Pokemon, so the slower Ditto will retain all of its PP and will Struggle last. 0 Speed IVs with a Relaxed nature aim to create the slowest untransformed Ditto. 252 Defense EVs are used with the Relaxed nature to minimize the amount of damage taken from opposing Struggle, while 4 Attack EVs give a slight boost to the damage output of Struggle. 0 Speed IVs and 31 IVs in every other stat give Ditto Hidden Power Ice, allowing it to significantly damage defensive Landorus-T. 30 Special Attack, 30 Special Defense, and 1 Speed IV can be used for Hidden Power Ground, which allows Ditto to countertrap Magnezone.
