Battle Bond (Patreon)

Two bodies, working in sync. Sharing emotions, thoughts, and abilities, pokemon who choose not to fuse in this moment experience physical alterations to their bodies as they adopt traits from their partner. Some call this Synchronized Evolution, some call it Stage 1 Fusion, but most call it Battle Bonding.  Pokemon who are especially close to one another experience battle bonding when they successfully begin working in sync, and are rewarded with a secondary typing that serves to buff their abilities. Many pokemon opt to work with Battle Bonding rather than fusion as it is less physically taxing on their bodies once a battle is over. It is difficult to Battle Bond outside of a fight or otherwise during a time of great distress or need. 

A concept I've been playing around with adding to On Borrowed Time is Battle Bonding (something seen with Ash's Greninja), and I'm still waffling on it depending on how much time I get in the comic to explore these things.