Other Options

Close Combat is an option over High Horsepower to OHKO Air Balloon Kingambit and deal more significant damage to Kyogre and Arceus-Water, but it is noticeably weaker against Necrozma-DM and Zacian-C, and the Defense drops make Calyrex-I much easier to KO. A Choice Band set that utilizes Tera Ice can overpower even the bulkiest Ice-resistant Pokemon after only a single Chilling Neigh boost. However, Calyrex-I's weakness to entry hazards and status as well as its inability to set Trick Room for itself while holding a Choice Band necessitates dedicated Trick Room and Healing Wish support from multiple teammates, which is often impractical. Mental Herb can be used to block Taunt from the likes of Miraidon and the Arceus formes when attempting to set up, but Calyrex-I is too infrequently targeted with Taunt to justify its use over other items, which Calyrex-I will almost always get value from.

Checks and Counters

Arceus-Water: The combination of Arceus-Water's typing, fantastic Defense, and access to moves like Will-O-Wisp and Dragon Tail leaves Calyrex-I with scarce hope of ever breaking past it, even with Terastallization.

Necrozma-DM: With its Steel typing and Prism Armor ability, Necrozma-DM can comfortably tank attacks from Calyrex-I, even after a Swords Dance boost, and threaten heavy damage in return. Necrozma-DM can also use an unboosted Calyrex-I as fodder to set up its own Swords Dance or Dragon Dance boosts. However, with Terastallization, Calyrex-I can set up on Necrozma-DM and potentially beat it, especially if Necrozma-DM is lacking a setup move.

Kyogre: Kyogre has sufficient bulk to avoid being 2HKOed by High Horsepower with only minimal defensive investment, and it can comfortably 2HKO Calyrex-I in the rain. Kyogre's presence also deters Calyrex-I from Terastallizing into a Fire-type to break past its teammates. However, Kyogre's lack of reliable recovery prevents it from repeatedly switching in against Calyrex-I and allows it to be worn down by Calyrex-I's teammates.

Ice-resistant Pokemon: When they're healthy, Ice-resistant Pokemon such as Zacian-C, Kingambit, and Chien-Pao can avoid being OHKOed by Calyrex-I and deal significant damage in return, usually defeating Calyrex-I outside of Trick Room. However, they are susceptible to falling to Calyrex-I when Trick Room is in effect or if Calyrex-I has enough boosts. Additionally, many Pokemon run Ice-resistant Tera types, such as Tera Steel on Giratina-O and Arceus-Ground and Tera Water on Arceus-Fairy and Gliscor.

Air Balloon Kingambit: An Air Balloon replaces Kingambit's Ground weakness with an immunity, which denies Calyrex-I the opportunity to OHKO Kingambit with High Horsepower after a Swords Dance. This allows it to beat Calyrex-I even in Trick Room unlike other Kingambit sets that can be removed by a boosted High Horsepower.

Unaware Walls: Unaware walls impede Calyrex-I's offensive output considerably, though they are typically found only on stall teams. Skeledirge can threaten to burn it with Will-O-Wisp and heal any damage taken with Slack Off—however, it does take considerable damage from High Horsepower—while Dondozo's typing and gargantuan physical bulk allow it to slowly wear down Calyrex-I without fear of being KOed.