Glastrier is a newer Legendary Pokemon in Sword and Shield's Crown Tundra DLC expansion.
It can be combined with Calyrex to form Calyrex Ice Rider. This particular version is an incredibly powerful Legendary. Galstrier can be used on its own, however, as a standalone battler.
By itself, Glastrier has pretty good stats, considering it is a Legendary Pokemon. It is extremely slow, working well in a Trick Room setting. It has a great physical Attack, decent HP, and very good overall defensive stats.
The best moveset for Glastrier in Pokemon Sword and Shield
Glastrier should be an attacker, first and foremost. If Trick Room cannot be put up, Avalanche is an incredible STAB move to use. It has decreased priority. If Galstrier is damaged prior to using it, Avalanche will double its power. There should be no problem pulling this off at normal speeds with Glastrier's defense.
This will be one of Glastrier's main coverage moves. It will do some serious damage to Pokemon that could cause trouble to it, such as Fire or Rock-types. Glastrier's Chilling Neigh ability gives it a boosted Attack stat whenever it faints an opponent. That will make a non-STAB High Horsepower very dangerous.
Swords Dance is almost a necessity to start a game. If it can be used, it will be able to knock out just about any Pokemon. This move raises the Attack stat, meaning it will be a good setup to deal some solid damage. When the Pokemon faint, the Ability will raise the Attack stat even more. Swords Dance is perfect to start the onslaught.
Body Press/Close Combat
The last move is a preference but should be one of these Fighting-type moves. Body Press uses the Pokemon's Defense stat. The higher the Defense, the more damage Body Press does. Close Combat does insane damage off the bat, but it lowers Defense and Special Defense. It really depends on the trainer's battling style.