Galarian Darmanitan

Among the Ice Types of Pokemon Go, Galarian Darmanitan is a bit of a glass cannon. It throws out some very high damage, and can even come semi-close to the top Shadows of the type, but it is pretty frail. That said, its future is potentially even greater. In the main series, Galarian Darmanitan, much like its normal forme that originated in Unova, has a special Zen Forme. This Ice/Fire Type forme is wildly powerful, but it currently only has a Fire Type STAB moveset to its name and we have no idea when/if it will make an appearance, so this version is definitely not a bad investment in-and-of itself!

Best PvE Offensive Moveset

• Ice Fang and Avalanche provide maximum damage
• Ice Punch is a weaker alternative, but it can provide a parting shot if used as a second move due to its low cost
• Tackle, Overheat, and Superpower are inferior options

Best PvE Defensive Moveset

• Ice Fang is greatly superior to Tackle on defense
• Superpower is strong and comes out fairly frequently, as well as providing strong counter coverage against Rock and Steel Types
• Avalanche is strong, but the fact that it shares a type with Ice Fang makes it less effective on defense
• Ice Punch comes out frequently, but it suffers from the same issue as Avalanche
• Overheat is powerful, but it's fairly easy to dodge and Galarian Darmanitan is far too frail to use it reliably.

Ice Fang is the best fast move for Galarian Darmanitan, since Tackle is such a bad move. 

Avalanche deals massive damage with STAB, and only costs 5 more energy than Ice Punch, which deals significantly less damage. Superpower costs the least amount of energy, and provides wide coverage, though it is not recommended to bait shields with it due to its self-debuff. Overheat costs the most amount of energy, but can threaten considerable damage if unshielded.