Implementing a Pokemon Battle System into a Roguelike

I recently started working through "RoguelikeDev Does The Complete Roguelike Tutorial 2018" by u/aaron_ds. When I reached the combat segment, I began to consider an alternative in the form of Pokemon's battle system. Every time you encounter an enemy, the game switches from the map view to an arena with player vs monster, and within that space, you can select certain abilities or tools that you have collected throughout the dungeon.

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How would you go about implementing a system like this? Have you seen anyone else try this, and if so, do you have a source?

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