Shadow Porygon2

Porygon2 sports superior bulk compared to its evolution, and almost identical bulk compared to its pre-evolution in Great League due to the nature of the CP cap. Porygon2's bulk is average at best, and its moveset is rather unusual and resembles that of Registeel. While Porygon2 doesn't enjoy the long list of resistances that Registeel does, its access to a cheaper Tri-Attack enables Porygon2 to benefit from a bait-and-nuke style of play in 1-shield scenarios. Notable wins may be surprising, and may possibly include Mandibuzz, Umbreon, Shiftry, Swampert, Tropius, and Umbreon, among others. Unfortunately, Porygon2's moveset is very inefficient, with very poor fast move damage output often leading to overkill damage from its charge moves, and inconsistencies when shields are in play. 

As a Normal-type, Porygon2 enjoys resistances against popular Ghost-types in this league, but that's mostly the only niche it has going for it. Due to the nature of its Lock-On movesets, Porygon2 would prefer to play in the later parts of the fight when shields are more likely to be used. Overall Porygon2 doesn't provide any real use in Ultra League; Giratina resists all of its moves and easily wins with Dragon Claw spam, which defeats one of the few niches that Porygon2 has.

Porygon2 lacks stats for Master League; at the least have a look at Porygon-Z (which also sucks)