Bugsmella

Game	Yo-kai Watch 2 BSFS
Origin	Unknown
Source	Multiple Reddit posts

After defeating a possessed Wicked Yo-kai (such as Badsmella in the Ironworks quest), if their befriending chance is met, they will be befriended in any subsequent battles where a Yo-kai can be befriended. This doesn’t stop until the player returns to the title or closes the game. It occurs because the possessed Wicked Yo-kai are not internally configured as mini-bosses, so they still have befriending rates despite having intentionally been programmed to be unbefriendable.

When befriending a Yo-kai while this glitch is in effect, all instances of the Yo-kai’s name and medal are replaced by that of the possessed Wicked Yo-kai. They will also use the possessed Yo-kai’s set of random nicknames, however their model will remain the same.

It is unknown if this bug is present in any other games.

(Image source and writing assistance: GenericUser)