Ditto

Normal

Ditto's ability Imposter allows it to transform into the foe when it is switched in, also copying all stat boosts and ignoring the Speed drop from Sticky Web. Thus, when equipped with Choice Scarf, Ditto can outpace all opposing Pokemon and Speed tie with those equipped with another Choice Scarf. Because of this, it's one of the most effective revenge killers, revenge killing setup Pokemon such as Mega Altaria, Mega Lopunny, and Mega Gallade and possibly countersweeping their teams. For this reason, Ditto also discourages setup, allowing you to play passively without being too worried of opponents taking advantage of it. Ditto is also a fantastic anti-stall Pokemon, as it essentially has unlimited PP because it can just switch out to recover its PP. It can also get free recovery and act as a cleric by switching into walls such as Chansey. It can also provide hazard clearance support by switching into Defog or Rapid Spin users such as Mantine or Excadrill. Ditto is a great scouting tool, as it allows you to see all of your foe's moves. Because of this, Ditto can run the role of a revenge killer or utility Pokemon depending on what it copies. However, Ditto has trouble against bulkier Pokemon such as Calm Mind Mega Latias. Ditto is very hard to bring into setup sweepers by a direct switch, so you must almost always sacrifice a teammate in order to successfully revenge kill the threat. Ditto only has 5 PP, so it'll get PP stalled very easily and can potentially end up giving the opposition a free turn. Ditto is very predictable because it always runs one set, so your opponent can play around it especially since they know the moveset that Ditto copies as well, and Ditto's low HP stat prevents it from revenge killing some Pokemon effectively. Lastly, Ditto can turn into a huge momentum sink if the opposing Pokemon doesn't have the moves you were expecting, such as super effective attacks to beat the opposing Pokemon or utility such as Heal Bell or Defog.