Like all other Gyms in Paldea, the Glaseado Gym building itself is simply used for registering Gym challengers. The Gym Test and Gym battle are both conducted outside the building, within Glaseado Mountain.
Nemona will challenge the player to a battle here if it is the third, fifth, or seventh Gym the player challenges. In case of the encounters at the third and seventh Gyms, the battle will take place before the Gym Test, while with the encounter at the fifth Gym, it'll take place after the Gym battle.
Gym Test
The Glaseado Gym Test is known as the Snow Slope Run. To pass it, the player must use KoraidonS/MiraidonV to slide down a designated snowboard course and make it to the goal within the target time of 90 seconds. Each missed gate adds five seconds to the timer.
After the player has defeated Grusha, they can attempt the Snow Slope Run again as many times as they want. There are three courses: the Powder Snow Course, the Blizzard Course, and the Sheer Cold Course, each of which gets unlocked after beating the previous one and is longer than the last. In the two last courses, Glalie are moving back and forth across the path to act as avoidable obstacles.
The Glaseado Gym appeared in Ice Battle! Cold-Eyed Grusha as Liko, Roy, and Dot arrived there for Liko's second Tera Training test. Before the test, the trio went to briefly enjoy bobsledding with some Cetoddle and met Grusha, who criticized Liko on having fun before the test and felt she wasn't taking it seriously. The test battle later commenced at the Gym's outdoor battlefield. Despite Liko's strategies and use of Terastallization, she still lost, with Grusha informing her afterwards that she had failed her test and refused to accept a do-over before leaving.
Cetitan is Grusha's third known Pokémon. It was used during Liko's Tera Training test battle against him, taking on her Floragato, who was swapped out for Hattrem. Hattrem put up a decent fight and dealt some damage to it, but Cetitian ultimately overpowered and defeated her. It then went up against Floragato once again, but this time, it was incapacitated when it choked on her Magical Leaf. Cetitan was then swapped out in favor of Altaria.
Altaria is Grusha's second known Pokémon and his ace in battle. During Liko's Tera Training test, it went up against Floragato after Cetitan was swapped out. It mostly had the advantage of flight until Floragato grabbed its legs with her vine and brought it crashing down with Acrobatics. Both Altaria and Floragato were soon Terastallized by their respective Trainers. A clash between Terastallization-boosted attacks followed, which eventually resulted in Floragato's defeat, causing Liko to lose the battle.
The Glaseado Gym appeared in the Scarlet & Violet arc. After Nemona had spotted who she thought was Penny (but was actually a disguised Scarlet) being taken away by a group of Team Star Grunts, she tried to call Scarlet, whose Rotom Phone was tossed out of the Flying Taxi by the Team Star Grunts and then caught by Grusha outside his Gym, after which he answered Nemona's incoming call. Nemona then told Grusha about the kidnapping she had witnessed.
Trivia
Glaseado Gym is the first Gym to not be located in a town or city since Cinnabar Gym in GenerationsII and IV.
It is the only Gym that is never located in a town or city, as the Cinnabar Gym was originally located on Cinnabar Island (Japanese: グレンタウンGuren Town).
