Brain Transplants are a technique occasionally used in amiibo training that require the use of external editing devices. It was first “discovered” by Amiibo Doctor during the Smash 4 amiibo metagame and helped increase understanding of how amiibo learn. Brain transplants can be performed with TagMo but not with Amiibo Powersaves.
A brain transplant takes the “mind” of a fully trained character and transfers it to a completely different character. For example, a fully trained Mario’s “brain” can be transferred into a Link amiibo. This Link amiibo would then act exactly as the Mario amiibo. Surprisingly, much of an amiibo’s special-move usage data was found to be stored in the game’s base AI rather than within the figure itself.
Brain transplanted amiibo were interesting to watch but were seldom entered into tournaments; when they were, they generally performed poorly and were swiftly defeated by properly-trained fighters. In Super Smash Bros. Ultimate, brain transplants are still possible, but are never used; this is because amiibo can store more training data due to the removal of custom moves.