Porygon @ Eviolite
Ability: Download
EVs: 252 HP / 252 SpA / 4 SpD
Quiet Nature
IVs: 0 Spe
- Ice Beam
- Thunderbolt/Tri Attack
- Trick Room
- Recover
I've been playing around with this guy quite a bit on the PU Ladder lately, to pretty good success. With the listed EVs and Eviolite, it's nearly impossible to OHKO this guy bar Fighting-Type coverage from the likes of Stoutland, Machoke, etc. and powerful special attacks such as Specs Leaf Storm from Exeggutor. Without Rocks, to my knowledge only Banded Stoutland, Banded Zweilous, or like a random Rampardos or something can 100% ensure the OHKO. Ice Beam is a must, giving Porygon a good matchup against most of the tiers more popular rockers, bar Monferno. Additionally, many of them tend to have better Phys. Def than Sp.Def, netting you an easy +1 just for switching in. Thunderbolt rounds out your offense, but Tri-Attack can work as a solid alternative that provides consistent damage, and works better when you can't come in on something that gives you the +1 Download boost. I prefer TBolt however, as many things that resist Ice Beam are weak to TBolt, and vice versa. Trick Room allows Porygon to support its team, as well as itself to deal some major damage under the right conditions. Remember, at +1 its modest (no pun intended) 295 Special Attack score is boosted to a very respectable 443, so those Ice Beams, TBolts, and Tri-Attacks are going to HURT anything that doesn't resist or is a dedicated special wall. Recover rounds out the set, allowing Porygon to stay healthy and more or less shrug off hits from anything that can't hit it super-effectively. Some caution must be used around dedicated wallbreakers however, as this set does not invest in Porygon's defenses.
There are a few reasons you'd want to use this guy over an alternative Trick Room setter such as, say, Carbink. The first, and perhaps the most important, is reliability. Carbink has a hard time doing everything it wants to do. It would like to set up rocks, possibly prevent your opponent from doing the same via Magic Coat or set screens if that's your thing, and set Trick Room before exploding so you can bring in a threat. Realistically, you'll manage maybe two of those things in a given match, if you're lucky, and you lose a Trick Room setter in the process nine times out of ten. With Porygon only having one real job and far fewer weaknesses defensively (just one, and Knock Off I guess), it can set Trick Room with ease and have freedom to fill other roles throughout the match as it's necessary. This leads me to the second advantage of Porygon: staying power.
With reliable recovery at its side, Porygon is capable of setting Trick Room multiple times throughout a match with relative ease. Porygon has an easy time setting TR and recovering off any damage against many defensive mons that can't immediately threaten it. Once you've revealed some of its coverage, many players will be hesitant to leave frailer threats such as Floatzel in on you for fear of being OHKOd, or in the case of Zebstrika simply losing 1v1, so it should be noted that Porygon can create many opportunities to do its thing even against offensive threats. This brings me to the final main advantage of Porygon: an actual offensive presence.
While Porygon's Sp.Atk is nothing too impressive, a mere Base 85, it can easily patch itself up to threatening levels via Download. While in theory, Download can be somewhat unreliable, in practice there are actually several staple defensive mons that are all but guaranteed to give you the +1 Sp.Atk boost such as Stunfisk, Gabite, Golem, Solrock, Pelipper, Gourgeist-Super, Baby Hippo, Tangela and Avalugg. Most of these mons can do relatively little to you, bar Toxic/Will-o-Wisp, though Golem is to be feared if Sturdy has not been broken and you run Bolt/Beam, due to the prevalence of Weakness Policy. Additionally, it can snag a +1 boost from offensive threats such as Floatzel, Relicanth, Exeggutor, Dodrio, Chatot, Gorebyss, Mightyena, and potentially many more in the case of mons with equal defenses. And of course, its worth mentioning again that you want to be careful on what you switch directly in to when dealing with the most powerful of these threats, they're threats for a reason. Even without the +1 boost however, Bolt/Beam is fantastic coverage in any metagame, particularly PU if I might add, and with full investment is going to cripple or KO anything it can hit super-effectively that isn't a dedicated special wall. Tri-Attack is also usable, dealing moderate damage with a 20% chance to royally screw your opponent via burn/para/freeze.
All in all, I'd say Porygon actually stands a cut above most Trick Room setters here in PU. While its true that there are other capable users such as Exeggutor, Carbink, and Duosion to name a few, Porygon is the only one capable of condensing everything it wants to do into a single moveset, leaving its user wanting for little. Exeggutor hates giving up a coverage move, Sleep Powder, or one of Giga Drain/Leaf Storm. Carbink has a hard enough time as is, and usually isn't doing its job more than once. Duosion is in a similar position as Exeggutor, in that it would like to fit Trick Room, all of its coverage, Recover and Calm Mind on one set, but it simply can't. Without coverage, you have to give up HP Fighting and lose to Dark Types or Shadow Ball and lose to other Psychic types, neither of which Duosion can afford. Mono-Attacking, while theoretically dangerous, is too situational, and would just end up as dead-weight in most match-ups with an opposing Dark-Type. None of this is a problem for Porygon, however. With Bolt/Beam you hit many things hard, leaving ample room for both Trick Room and Recover without giving much of anything, really. Basically, I never find myself saying "I wish I had used x coverage move instead!" when using this guy. Additionally, with its typing Porygon actually provides some decent synergy with other Trick Room setters such as the aforementioned mons, Gourgeist-XL (probably the best partner as it is immune to Fighting and can even shrug off Knock Off, the only Dark attack Porygon really cares about, if running Colbur + Synthesis), and Missy.
I also think that a defensive duck is probably viable, something like Discharge/Foul Play/Recover/Toxic for the moveset, with EVs being customizable to the needs of your team (either Phys.Def or Sp.Def), but that's just speculation because I haven't actually used this or found an optimal spread. It's something to think about, however.
TL;DR don't sleep on this duck