Ditto is a rather unique Pokemon, as it has the ability Imposter, which allows it to copy the foe's moves and stats, apart from HP. This allows it to function as a decent anti-offense option and reliable revenge killer, as, with a Choice Scarf, it'll almost always outspeed the opposing Pokemon. Because of how Imposter functions, Ditto will have any entry hazard effects applied before it transforms, meaning that it'll only take neutral damage from Stealth Rock and ignore the Sticky Web Speed drop, allowing it to be a solid answer to Sticky Web teams. Ditto can also use its ability to scout movesets, providing information on what the opponent is running. Even though Ditto is decent against more offensive Pokemon, it struggles against bulky defensive set-up Pokemon, like Clefairy and Musharna, because Ditto is forced to run a Choice Scarf to properly function as a revenge killer. Ditto also has a rather low HP stat, meaning it struggles to switch in or take hits, even when transformed. Imposter and Transform also fail against Pokemon that have set up a Substitute, leaving Ditto unable to revenge kill Pokemon like Oricorio-G and Alolan Dugtrio. While Ditto can act as a deterrent to certain setup Pokemon at Team Preview, it often struggles in practice, as the opponent can often play around it and weaken it enough for it to be unable to function as intended.