LogFAQs > #956943423

Porygon-Z has a huge 135 base Special Attack, decent bulk, great abilities in Adaptability and Download, and a great movepool. Hyper Beam is great in the 1v1 format as long as you can guarantee a KO and Adaptability increasing STAB from 1.5x power to 2x and off it's base Sp. Atk, it's pretty much a guarantee to anything that doesn't resist Hyper Beam. It also gets access a slew of great options like Thunderbolt for weakness, Tri-Attack for less drawbacks than Hyper Beam, Body Slam if you want a great chance to paralyze, Lock-On + Zap Cannon for some shenanigans.

Gorebyss on the other hand is a bit too balanced in base Stats and has low base stats in the wrong places. It's lower speed prevents it from being a good attacker and it's lower HP makes it just frail enough to not be able to survive many hits. It's abilities require the setup of Rain. What Gorebyss does get though is Shell Smash which it can take advantage of with it's lower Speed to setup the first turn and outspeed and KO with Hydro Pump the next.

Gorebyss can prevent Porygon-Z's Download ability from raising it's Special Attack if it invests enough EVs into Special Defense but can't do much about Adaptability. Also while Gorebyss can survive a barely survive a Thunderbolt or Tri-Attack with an Assault Vest, that'd prevent any set up of Shell Smash or Rain Dance and doesn't prevent Hyper Beam from completely obliterating it and getting sent to the Shadow Realm.

Porygon-Z gets my vote.

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