Power Progression on low complexity Spirits is enabled by default when you are at the Beginner experience level. With Power Progression, when you gain a Power Card you receive a predetermined card instead of choosing from 4 Power Cards. This can help you learn the game with one less thing to think about.

When you're ready, you can move up to Intermediate experience level from the Options screen (also, you may be prompted at the end of a game), which will disable Power Progression for all Spirits. Or, you can toggle Power Progression for individual spirits in the New Game screen by viewing their full Spirit Panel (right-click or double-tap) and toggling the option at the top right.