With great base 100 / 120 / 120 bulk and a decent base 90 Special Attack, it's no surprise Suicune has been a good Pokemon ever since its introduction in GSC. In those days, it would either run a phazing set consisting of Surf, Roar, Toxic, and Rest or a RestTalk set comprising Rest, Sleep Talk, Surf, and Ice Beam, which served as a bulky check to a whole bunch of Pokemon in OU. However, Suicune really found glory in ADV, where it was famed as arguably the best Calm Mind user in OU. It would run a Substitute + Calm Mind set, a defensive RestTalk set with Roar, or a defensive Calm Mind set with Surf, Calm Mind, Rest, and either Roar, Sleep Talk, or Ice Beam, which later became known as "CroCune," after the player who innovated it. Not much changed for it in DPP, as it ran mostly the same sets. One thing that did come in DPP, however, was the introduction of the offensive Calm Mind set, as with investment, Suicune can deal heavy damage to the opposing team after a boost or two despite its below average Special Attack stat. BW came and went, and with the coming came the advent of Suicune in UU. Suicune remained a great Pokemon in that tier, where its bulky setup capabilities made it a staple on many teams.

ORAS has been very kind so Suicune so far. Its tier, UU, is infested with Fire-types just begging for Suicune to come in and set up. It takes almost nothing from pretty much all Fire-types in UU (barring secondary STAB attacks from Rotom-H and Choice Specs Chandelure, both of which fail to OHKO) and can heal off any status through Rest. Also, thanks to its great bulk, it can avoid a 2HKO from many Pokemon and proceed to set up on them. A RestTalk RoarCune is also popular for its ability to sponge powerful attacks and phaze setup sweepers.

"So, if it's boosted, hit it with a strong, super effective attack, right?" Of course, that would be the optimal course of action. However, there is a lacking of physical Electric- and Grass-types in UU. That said, Pokemon such as Shaymin, Roserade, Rotom-C, Mega Ampharos, and Heliolisk can all put some heavy damage on Suicune. Also, Choice Band Heracross can 2HKO it and doesn't fear burns from Scald thanks to Guts. Taunt users are also effective at shutting down Suicune, as they limit it to a single move on most sets and prevent it from recovering with Rest, boosting with Calm Mind, or doing anything if they're already asleep by virtue of Sleep Talk being a status move. Entry hazards limit Suicune's ability to come in and immediately start boosting, making it a lot easier for other Pokemon to take it out. Finally, other phazers such as Empoleon can remove all of its stat changes provided Suicune isn't the opponent's last Pokemon.

Very few Pokemon have managed to stand the tooth of time like Suicune has, and whatever tier it roams, it will always remain one of the better defensive setup sweepers and a big threat to prepare for. Try it out!