Porygon2's good natural bulk combined with its access to Recover makes it one of the best Eviolite users in the game. Unlike many other Eviolite users, Porygon2 also has a decent Special Attack stat alongside BoltBeam coverage to give it some offensive capability. The Virtual Pokemon is also blessed with two amazing abilities in Trace and Download to assist it both offensively and defensively Porygon2 even has access to Trick Room and, due to its decent power, coverage, and bulk, makes for one of the best Trick Room supporters for dedicated Trick Room teams.
On the flipside, Porygon2 no resistances to take advantage of, and only possesses an immunity to Ghost, a real hindrance for a defensive Pokemon. While it only has one weakness, that weakness happens to be to Fighting, a common and powerful offensive type in OU. Porygon2's reliance on Eviolite prevents it from holding Leftovers, making passive damage even more harmful. Despite these flaws, Porygon2 still makes for a great niche counter to many popular Pokemon with Trace, and it provides an excellent combination of Trick Room support and sweeping for Trick Room teams.
Porygon2's excellent bulk and access to the rare Trace ability make it a great switch-in to a variety of offensive threats. Trace allows Porygon2 to shut down Intimidate users such as Gyarados and Landorus-T, trap Dugtrio with its own Arena Trap, use Dragonite's Multiscale against it, wall Heatran and Jolteon (and Thundurus-T lacking Focus Blast) with their immunity abilities, and even heal its status with Natural Cure from Celebi or Starmie. Thunderbolt provides strong Electric coverage for better handling Pokemon such as Gyarados. Ice Beam completes the BoltBeam combination, allowing Porygon2 to hit every OU Pokemon for neutral damage bar Magnezone and Thick Fat Mamoswine. It also gives Porygon2 much appreciated coverage against Pokemon such as Dragonite, Garchomp, and Landorus-T. Toxic gives Porygon2 a great status weapon to use against bulkier Pokemon that do not fear its BoltBeam coverage. Hidden Power Fire, on the other hand, lands a much harder hit against Magnezone, Ferrothorn, and Scizor, which all generally give Porygon2 trouble. Thunder Wave is also an option in case you feel the ability to cripple offensive Pokemon with paralysis is more important than Toxic poison or Fire-type coverage. Finally, Recover is essential for keeping Porygon2 alive throughout the match, letting it switch in and wall opposing threats more effectively.Team Options & Additional Comments >>>
Porygon2 shines as one of the best Trick Room supporters for dedicated Trick Room teams, and it's capable of taking advantage of the move itself when given the chance. While there are much better standalone Trick Room sweepers, Porygon2's excellent bulk with Eviolite gives it plenty of opportunities to switch in and reliably set up Trick Room. The combination of Thunderbolt and Ice Beam gives Porygon2 great BoltBeam coverage, helping it make the most of Trick Room by hitting most Pokemon at least neutrally before they have time to react. Hidden Power Fire covers Scizor and Ferrothorn, two major threats to many Trick Room teams, as well as Pokemon such as Forretress and Magnezone. Tri Attack is Porygon2's best STAB and its most powerful move. It also lets Porygon2 net a OHKO or 2HKO on Pokemon such as Mamoswine, Kyurem-B, Rotom-W, and Volcarona with entry hazard support, a feat Porygon2's other moves fail to accomplish. Recover can also be used to keep Porygon2 healthy throughout the match, bolstering its great bulk and letting it set up Trick Room more often to support its teammates.Team Options & Additional Comments >>>
Hidden Power Fighting hits Magnezone and Ferrothorn harder than Thunderbolt and Ice Beam do, and it also nails Mamoswine, one of the few Pokemon to resist the BoltBeam combination. Likewise, Hidden Power Ground hits Magnezone very hard, hits Heatran far harder than Thunderbolt does, and synergizes well with Ice Beam. As with Trick Room, Porygon2 can serve as a reliable Gravity supporter for teams based on the move. Porygon2 can also take advantage of Gravity itself by using Thunder and Blizzard over Thunderbolt and Ice Beam. Even without Gravity, Porygon2 can use Thunder and Blizzard in rain and hail, respectively. However, rain is generally the better of the two options as hail damage causes Porygon2 to be worn down much more quickly than it would be otherwise. Defensive Porygon2 sets can also use Magic Coat to bounce back disruptive support moves such as Taunt and Toxic.
Porygon2 has very little in the way of boosting moves, and so Psych Up can be used to steal boots from opposing sweepers. However, Porygon2 can only really take advantage of Calm Mind boosts, and many Calm Mind sweepers such as Reuniclus and Keldeo have ways to beat Porygon2 regardless. Porygon2 could try to boost its Special Attack with Charge Beam, but the move is initially very weak and somewhat unreliable. A set with Agility can be used to boost Porygon2's Speed and works similarly to one with Trick Room. While such a set would have less bulk than the Trick Room set and will still be outsped by faster Choice Scarf users such as Terrakion and Keldeo, it would not be restricted by a timer nor constrain teambuilding as much. While it doesn't boost any of Porygon2's stats itself, Icy Wind offers Ice coverage and the ability to lower the Speed of the opponent's sweepers. However, it's generally more effective to paralyze opponents with Thunder Wave and use the more powerful Ice Beam for coverage.
Although Eviolite is almost mandatory for Porygon2, a Choice Specs set is feasible due to the boost it offers to Porygon2's already great coverage. Porygon2 also learns Trick which works well in conjunction with Choice Specs, enabling Porygon2 to cripple many bulky switch-ins. Analytic works well with Porygon2's low Speed by giving it a 30% power boost to all of its attacks whenever it attacks second. However, Trace offers much better utility for defensive sets, and the main offensive set that Porygon2 should be running, the Trick Room set, will rarely attack second and appreciates the possible Special Attack boost from Download.
Checks and Counters
Magnezone resists Porygon2's BoltBeam coverage and Tri Attack and is immune to Toxic, making it a great switch-in to the defensive sets. Substitute sets in particular can set up on defensive Porygon2 lacking Hidden Power Fire and offensive sets lacking either Tri Attack and Hidden Power Fire or a Download Special Attack boost. Mamoswine also resists BoltBeam and so can handle Porygon2 without Tri Attack, KOing even defensive Porygon2 with Earthquake followed by Superpower. Fighting-type Pokemon in general threaten Porygon2 with super effective STAB attacks. Breloom, Keldeo, and Terrakion are a few examples of powerful Fighting-type Pokemon capable of forcing out or KOing Porygon2. Conkeldurr not only threatens Porygon2 with its STAB Fighting-type attacks, but it can also take advantage of status with Guts and outspeed Porygon2 under Trick Room.
Besides the offensive Pokemon mentioned earlier, there are a few other ways of handling Porygon2. Blissey, Chansey, and specially defensive Celebi fear very little from Porygon2; even Toxic can just be healed away with Heal Bell or Natural Cure. Although most Heatran sets are walled by Porygon2, specially defensive Heatran with Toxic is capable of beating it one-on-one. Due to its lack of Leftovers, passive damage harms Porygon2 more than it does other walls. Various sources of passive damage such as Toxic, Toxic Spikes, Will-O-Wisp, Sand Stream, and Snow Warning are good ways of wearing Porygon2 down and keeping it in check.