Where to find Bagon in Sword & Shield

Overworld: Tunnel to the Top
Static Encounter: Tunnel to the Top (Overcast)
Max Raid Battle: Ballimere Lake (Only in Sword), Frigid Sea (Only in Sword), Giant's Bed (Only in Sword) + 2 more

Bagon also appears in

How to get Bagon in Sword & Shield

It appears in any weather.

Its base catch rate is 45 out of 255 (higher is easier); the catch rate calculator works out your odds with each ball. For the look, the best colour match is Heavy Ball, Moon Ball or Quick Ball.

Evolution: Bagon → Shelgon (Level 30) → Salamence (Level 50).

Bagon in every game · Pokémon Sword & Shield interactive map (Galar)

All Sword & Shield locations