Pokémon Battling #

Various battle situations. From left to right: (a) Wild battle. (b) Trainer battle. (c) Running away from battle. (d) Catching a Pokémon. (e) Pokémon fainting and Player blacking out.

Half of Pokémon’s objectives involve battling and winning against other trainers. However, teaching battling is not required to make an agent capable of completing Pokémon with RL.

The Battle System #

The Pokémon battle system is pretty straight forward. Pokémon is an advanced game of rock-paper-scissors. Pokémon have moves that can be used to either inflict status effects against other Pokémon, damage other Pokémon or boost their own abilities or self-heal. The strength of each move is affected by the strengths and weaknesses of each Pokémon relative to the move and overall stats. Moves are given priority based on the move and a Pokémon’s SPEED stat. Damage is based on the Pokémon’s ATTACK, SPECIAL and DEFENSE stats depending on the move. Additionally, moves can miss based on the move’s and Pokémon’s ACCURACY stats.

During battles, the player can additionally switch their current Pokémon in-battle or use items to heal their Pokémon.

There are two types of battles in Pokémon

Wild battles where the agent will battle against a single Pokémon. Wild battles begin with a random encounter in grassy areas or dungeons.
Trainer battles place the player against a team of one or more Pokémon. Trainers have access to the item and party switch actions like the player.

Battles end when all Pokémon on one side have fainted. Fainting is when a Pokémon’s health drops to zero. Additionally, during a wild battle, the player has the option to run and leave the wild battle or catch the opposing Pokémon and have the opposing Pokémon join their party.

If the player’s Pokémon knocks out the opposing Pokémon, the player’s Pokémon gains experience (EXP). With enough EXP, a Pokémon will level up. Leveling up provides a mechanism to increase the Pokémon’s stats. Leveling up to increase stats gives a mechanism to ignore worrying about battling. If the agent “grinds,” that is, let Pokémon level up or retry trainers infinite times, the agent will eventually win outside of a couple of very unlikely situations.

We ignored creating a policy for battling and focused on providing suitable conditions for leveling up when needed.