Regice is one of the best special walls in ADV, being able to keep pace with the best special attackers in the tier. Even with an unappealing weakness to Rock-type attacks, Regice can use attackers with such moves to its advantage, becoming an effective lure for these Pokemon. Its ability to take a hit and strike back with Ice Beam or Thunderbolt will often result in the unexpected death of some of the opponent's best sweepers.
Regice's standard defensive set has two different variations. The first is the standard RestTalk set that focuses on countering threats like Raikou and Zapdos without ever really being in danger of losing health. If you decide to use Sleep Talk on Regice, make sure to use Seismic Toss, as Thunderbolt won't beat any Calm Mind user one-on-one. The second variation is a Psych Up set, which lets Regice set up alongside Calm Mind users by copying their boosts, allowing Regice to sweep with Thunderbolt and Ice Beam. These sets work very similarly, but they are distinctively different sets, both of which turn Regice into a very sturdy wall.
Max HP and 112 Defense EVs allow Regice to survive Choice Band Aerodactyl's Rock Slide in sand, the most ferocious of attacks that Regice would normally be afraid of. It also allows Regice to take hits better from Gyarados, Salamence, and Swampert; Regice can then threaten all of them with Ice Beam except for Swampert, who it can Rest against. 60 Special Defense EVs prevent Raikou from ever 3HKOing Regice with +1 Thunderbolt, even in sand. This is generally the strongest special attack Regice has to concern itself with. 20 Speed EVs get the jump on minimum Speed Swampert, allowing Regice to nail it with Ice Beam. The rest of the EVs are placed into Special Attack to raise Regice's offenses to a respectable level.Team Options & Additional Comments >>>
Unlike the previous set, this Regice uses its solid base 100 Special Attack to hit hard right off the bat. The key to this set is that Snorlax and Blissey are sometimes the only answer to Regice; Explosion weakens them to the point that Dugtrio is able to revenge kill them. Yes, this means Dugtrio should be used with this Regice. This Regice also excels on offensive teams based around special attackers like Gengar, providing a good check to threats such as Zapdos and Celebi while weakening specially defensive Pokemon with Explosion. Thunder Wave is usually used in the last slot, easing Regice's prediction and allowing it to be a general nuisance to switch-ins that Explosion can't touch, such as Jirachi. Hidden Power Fire can be used on said Steel-types and prevents specially defensive Forretress from setting up on Regice.
156 Attack EVs let Explosion to do a minimum of 63% to Snorlax, allowing Dugtrio to revenge kill it 100% of the time, even without sand. Maximized Special Attack makes sure that Regice can actually threaten standard Pokemon with Ice Beam and Thunderbolt. The remaining EVs are dumped into HP to retain bulk. Regice has never been too concerned about its Speed, which is why a Quiet nature is used. Detracting from your other stats is never a good idea and will result in a Regice that can't take hits well enough.
A Curse set can be used to boost Regice's Defense and turn it into a hefty tank. Earthquake, Superpower, Explosion, and even Counter are all options that can be paired with Curse. Superpower can surprise Tyranitar, while Counter can strike back hard against the physical attackers that Regice is likely to take on. Thunder is an option for guaranteeing the kill on specially defensive Skarmory and for threatening Suicune with a possible 2HKO, but it has accuracy issues. Toxic can be used to threaten defensive teams, but Steel-types are often the first switch-in to Regice.
Checks and Counters
Metagross is an excellent counter, resistant to Ice Beam and able to threaten Regice with Meteor Mash. Any strong Rock-type attack will seriously dent Regice, but be careful about Regice striking back with Ice Beam. Forretress can try to set up Spikes on most Regice, but make sure Regice isn't carrying Hidden Power Fire. Jirachi can set up on non-Psych Up variants of Regice without being threatened.
Defensive Pokemon like Blissey will never feel very threatened by Regice and can use the free turns gained to support the team. Heracross and Houndoom are both very threatening to Regice with their strong attacks, as well as any user of Focus Punch. One of the best ways to deal with Regice is to take advantage of its lack of instant recovery, weakness to Spikes, and lack of a sandstorm immunity to your advantage.