Where to catch Hattrem

In Paldea (Scarlet & Violet)

• Glaseado Mountain — Walk
• South Province (Area Six) — Walk
• Tagtree Thicket — Walk

In Kitakami (Scarlet & Violet – The Teal Mask)

• Kitakami Wilds — Walk
• Timeless Woods — Walk

Hattrem — full Pokédex entry