To evolve Basculin into Basculegion in Pokémon Legends: Arceus, it needs to take recoil damage. Our Pokémon Legends: Arceus Basculin evolution guide explains how to evolve Basculin into Basculegion.
How to evolve Basculin into Basculegion
Based on our tests, Basculin evolved when taking around 260-300 recoil damage at minimum. To evolve yours, take your Basculin to an area with weaker Pokémon and make it use Wave Crash or Double-Edge until you get the notification that you can evolve it.
The recoil damage does not need to happen in the span of one battle, so feel free to heal up your Basculin as you need to.
Explaining our methods
Strangely enough, the amount it needed before we were able to evolve it were different across three tests.
Our first two Basculin were male and the third was female. We didn’t use Strong or Agile Style moves. We used a mix of Wave Crash and Double-Edge, since both of those deal recoil damage.
Our first Basculin took 267 damage before we were told we could evolve it. The second Basculin took 296 damage. The third took 302 damage before we got the evolution prompt. Each attack did around 15-20 recoil damage to our Basculin.
We battled weak Pokémon, so our Basculin were able to one-hit each opponent using its recoil-causing move. Basculin #1 took 10 battles to evolve, Basculin #2 took 14, and Basculin #3 took 16.
Other sources, like Serebii.net and Bulbapedia, note that Basculin needs to take 294 recoil damage, which conflicts with our own data. That all being said, we haven’t quite figured out the magic number to evolve Basculin, as it has some influencing factor that we can’t quite see.