Porygon2

Even though Porygon2 is an NFE Pokemon, it can still shine in the OU tier due to its ability to check common threats. Its Trace ability allows it to copy the ability of any Pokemon it switches into; this is extremely useful, as it gives the defensive duck a unique niche in the OU metagame. Porygon2 can also be employed as an excellent support Pokemon on a dedicated Trick Room team, as it is able to both set up Trick Room and take advantage of its effects. Even though Porygon2's defensive stats are good, they are by no means great, so Porygon2 will often struggle with powerful STAB attacks from threats such as Shaymin. Additionally, while Porygon2's Normal typing affords only one weakness to Fighting-type attacks, any Pokemon who utilizes Fighting-type attacks will often be able to deal significant damage to it. Despite these drawbacks, Porygon2's unique abilities make it a solid choice on any OU team in need of its specific services.