[OVERVIEW]
Ditto's unique ability Imposter causes it to transform into the opposing Pokemon, also copying any stat changes. These stat changes also overwrite whatever was affecting Ditto initially, allowing Ditto to decimate most Sticky Web teams. With a Choice Scarf, Ditto can always outspeed what it transforms into, unless that Pokemon is also holding a Choice Scarf. This allows Ditto to operate as an excellent revenge killer. In addition, Ditto can handle stall teams by copying recovery, hazard removal, and cleric support, and its transformations come with fresh PP. With a reliable Regenerator partner, Ditto can have pseudo-infinite PP and win the long game against stall. Ditto also provides team support by scouting movesets.
In OU, Ditto is best suited for bulky teams as an anti-setup, anti-offense, and anti-stall option. However, because Ditto is forced to run Choice Scarf to avoid Speed ties, it has trouble with defensive setup Pokemon like Calm Mind Clefable and Reuniclus. Ditto can also be difficult to bring in safely against offensive teams due to its low HP stat and the likely low bulk and high offensive stats of the Pokemon it seeks to revenge kill. Additionally, Imposter and Transform are blocked by Substitute, leaving Ditto and its team vulnerable against setup sweepers that utilize said move, such as Zygarde and Gyarados.
[SET]
name: Imposter
move 1: Transform
move 2:
move 3:
move 4:
item: Choice Scarf
ability: Imposter
nature: Relaxed
evs: 252 HP / 4 Atk / 252 Def
ivs: 0 Spe
[SET COMMENTS]
Moves
========
Transform is the only move Ditto learns. It will likely not see use—Imposter will usually transform Ditto immediately upon switch in, and an otherwise untransformed Ditto is extremely frail and can be easily OHKOed—but it is required for a valid set.
Set Details
========
Imposter lets Ditto immediately transform into its foe upon switch in and is what gives Ditto its viability. Without Imposter, Ditto would be extremely slow and vulnerable while it wastes a turn to use Transform. Choice Scarf is used to avoid Speed ties. Unless the foe is also holding a Choice Scarf, Ditto will outspeed it and be able to act as a revenge killer. 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.
Usage Tips
========
Use Ditto to revenge kill offensive threats. Ditto can apply heavy pressure on opponents by copying their wallbreakers. Copying powerful Mega Evolutions, such as Mega Medicham and Mega Charizard Y, can be especially devastating, as the typical counterplay of revenge killing is made difficult by Ditto's Choice Scarf. Early-game, Ditto can be sent in or lead off with to scout movesets. Against stall teams, attempt to switch Ditto into Knock Off to have its Choice Scarf removed. Without Choice Scarf, Ditto has the freedom to switch moves and has its effective PP increased from 5 to 20, allowing it to PP stall when paired with teammates with Regenerator. Ditto can then proceed to counter Mega Sableye and copy cleric support and entry hazard removal.
Team Options
========
In OU, Ditto is best suited for bulky teams that need support versus offensive setup, offense, and stall teams. Since Ditto punishes setup, extremely bulky Pokemon like Chansey, which typically require setup to break through, can make very effective partners. Teammates with Regenerator teammates such as Tangrowth and Amoonguss allow Ditto to PP stall defensive Pokemon. Entry hazard removal from Mew, Tapu Fini, Skarmory, or Zapdos keeps Ditto healthy throughout the course of a match. Pivots able to use U-turn and Volt Switch, such as Landorus-T, Magearna, and Rotom-W, are able to bring in Ditto safely. Pokemon able to handle Calm Mind users are appreciated; physical wallbreakers such as Hoopa-U are nice in this regard. Hoopa-U is also able to punish Substitute users with Hyperspace Fury. Entry hazard setters like Ferrothorn, Heatran, and Landorus-T can break opposing Focus Sash and potentially put defensive Pokemon in range of Ditto's attacks.
[STRATEGY COMMENTS]
Other Options
=============
Due to Ditto's one-dimensional nature, it lacks many viable other options. An IV spread of 31 / 30 / 31 / 30 / 31 / 0 could be used to give Ditto Hidden Power Fire, creating better Tapu Lele and Latios sets when copying those. However, Ditto then loses out on the ability to damage defensive Landorus-T.
Checks and Counters
===================
**Substitute Users**: Substitute blocks Imposter, so Pokemon that set up behind Substitute, including Zygarde and Gyarados, can nullify Ditto and proceed to tear apart its team.
**Calm Mind Users**: Pokemon that set up with Calm Mind such as Reuniclus and Clefable can take advantage of the fact that Ditto is Choice locked to recover on it, damage it, or use it as further setup fodder.
**Choice Scarf Users**: If Ditto transforms into an opposing Choice Scarf user, it will be forced into a Speed tie. In addition, Choice Scarf users that are faster than the Pokemon Ditto is transformed into can revenge kill it.
**Entry Hazards**: Ditto is vulnerable to Stealth Rock, Spikes, and Toxic Spikes, since it takes entry hazard damage before Imposter triggers.
**Opposing Ditto**: If an opposing Ditto is already transformed, Ditto cannot transform into it and becomes useless.
