To evolve Basculin into Basculegion in Pokémon Legend: Arceus, it needs to take recoil damage. Ours Pokémon Legend: Arceus The Basculin Evolution Guide explains how to evolve Basculin into a Basculegion.
How to evolve Basculin into Basculegion
Based on our tests, Basculin has evolved with use Minimum 260-300 damage on recoil. For your development, take your Basculin to an area with weaker Pokémon and use it Wave collision or Two sides until you get the message that you can develop it.
The recoil damage doesn’t have to happen for the duration of a battle, so feel free to heal your Basculin if you need to.
Explaining our methods
Oddly enough, the amount it took before we could develop it was different across the three tests.
Our first two basins are male and the third is female. We don’t use Strength or Agility moves. We use a combination of Wave Crash and Double-Edge, as both deal recoil damage.
Our first Basculin took 267 damage before we were told we could evolve it. The second Basculin takes 296 damage. The third takes 302 damage before we get the evolution prompt. Each attack deals about 15-20 recoil damage to our Basculin.
We’ve been fighting weak Pokémon, so our Basculin can take out each opponent with its recoil. 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 data. All that said, we still haven’t found the magic number to grow Basculin, as it has some influencing factors that we can’t see.
https://www.polygon.com/pokemon-legends-arceus-guide-pla/22910623/basculin-basculegion-evolve-recoil-damage Pokémon Legends Evolution Guide: Arceus Basculin