SSBU: Pyra and Mythra

Pyra and Mythra are the two personalities of a Living Weapon known as the Aegis, being literally inseparable since they share a single body. In their appearance in Super Smash Bros., they can switch between each other at will, share a single slot in the fighter roster, and are meant to be a "complimentary contrast" duo with each other with their literal fire power and light speed respectively.

Example of:
The Dividual