Vaporeon

Vaporeon is stuck in the middle of two paths in DPP OU. On one hand, Vaporeon has the second highest Special Attack stat of viable Water-types and, because of its great HP stat, is bulky enough to be a utility counter to many common threats such as Gyarados, Tyranitar, Gengar, and Heatran. Its low weight also makes it resilient against Grass Knot, helping it against foes such as Jirachi, Empoleon, and Infernape. On the other hand, Vaporeon has access to rare utility moves such as Wish, Haze, and Heal Bell, making it potentially a great support Pokemon. Water Absorb also is a fantastic ability, as it shuts down premier threats such as Gyarados, Kingdra, and Empoleon and makes them more hesistant to use their strongest attacks lest they heal Vaporeon. Against teams that don't have the tools to deal with it, such as rain teams, more defensive Vaporeon sets can be oppressive to deal with by scouting with Wish + Protect and healing against rain-boosted Water-type attacks.

Unfortunately, the modern DPP metagame is mostly inhospitable to Vaporeon. As a grounded Water-type, Vaporeon is hugely weak to residual damage from sand, all three entry hazards, and status. Unlike other grounded Water-types such as Suicune and Starmie, Vaporeon does not provide enough immediate offense or utility to be relevant. Suicune's significantly higher physical bulk, Speed, and access to Calm Mind make is more preferable as a utility offensive threat, while Starmie's great Speed and access to Rapid Spin make it a superior choice to Vaporeon. As a Choice Specs Water-type, Empoleon is preferred to Vaporeon, as Empoleon's Steel-typing, slightly higher Special Attack, and access to Grass Knot outclass Vaporeon marginally higher Speed. The Steel-typing helps against residual damage and hide its item in sand. Vaporeon also struggles as a wall, as Milotic is bulkier and has access to instant recovery with Recover, while other defensive Water-types such as Swampert, Quagsire, and Gyarados have beneficial secondary typings. The additional turn for Wish to activate helps it pass Wish; however, that additional turn makes it harder for Vaporeon to survive against residual damage when it desperately needs to heal itself.

Vaporeon also struggles to deal with many common threats. Vaporeon does not enjoy absorbing strong attacks from even foes it wants to check, such as Infernape's Close Combat, Tyranitar's Crunch, Gyarados's +1 Earthquake, and Heatran's Explosion. Vaporeon needs full investment to even remotely take on these foes comfortably. However, defensive Vaporeon is extremely passive, as it needs two slots to afford Wish and Protect. Vaporeon despises dealing with Clefable, as it is bulky enough to survive any non boosted Water-type attack and threatens it with Knock Off. Vaporeon's best niche is passing 101 HP Substitutes against bulky Pokemon. While Vaporeon can work as a standalone offensive threat, it is not recommended for use in DPP OU, as it is often outclassed in whatever role it tries to fulfill.