Pokemon Artificial Intelligence [closed]

Question

I'm working on a thesis about programming an AI combat system for Pokemon (To be implemented in Showdown!). However, I would like to include historical information about the existing implementations of Pokemon AI. This information would offer valuable context to my thesis.

I have been scouring the internet for some sort of algorithm that explains how the AI Trainers make their choices, but have found nothing promising. I realize the fan-games have implemented some more interesting AI systems for their trainers, these would be interesting to see as well.

What I am looking for is examples of the methods used for Pokemon Battle AI decision making used in Pokemon videogames, whether from main series by Nintendo or the many fan-games out there. I realize most of these pose no challenge to an experienced player, but I don't mind, I only wish to compile historical information on previous Pokemon AI attempts.

Answer 1

First off, I want to say that this particular case can be approached as a generic AI problem and solve it by training a neural network that has for input layer whatever information is relevant in the battle (such as health of the Pokémon, number of items, PP of the attacks, etc...) and having as output layer the different actions to take.

If you want to take that approach, and you have no idea how neural networks work, you can look for an introduction to the topic (there are videos, books, articles, etc...) and I'd suggest the approach described in Evolving Neural Networks through Augmenting Topologies to train and evolve your AI. For abstract, the paper proposes an approach to use genetic algorithms to evolve the topology (the connectivity) of neural networks.

Of course, training the AI requires to have it play multiple times, and using the feedback to improve it.

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I cannot really comment on AI of third party games, although we can talk about the AI bot created by drac5290 who was kind enough to publish the decision tree it uses combat. We can consider it an expert system.

Note: Whatever it sucks or not is debatable. The AI beats the Elite Four of Pokémon Blue, but it was given arguably strong Pokémon to battle and an endless supply of healing items. Also, there are new mechanics in newer Pokémon that it doesn't have to bother with.

The decision tree is the following (Yes to the left, No to the right):

As you see, it requires to calculate if the Pokémon currently out will die of an attack of the enemy in the next turn, it also requires to determinate what Pokémon will take less damage and which one will do most damage to the enemy.

Also, it doesn't have much actions, it only does: Switch, Attack (with the best attack available), and Heal using items. As far as I can tell, inflicting status effects to the enemy is not taken into account.

Answer 2

The AI for Pokemon depends on the version, but it's nothing really advanced. I'll talk about a bit red/blue/yellow in this answer, sources below.

The AI picks a move using rejection sampling from the moves it considers usable, which moves it considers usable depends on the turn the Pokemon is out and what kind of trainer it is.

For example, on turn 1 if the trainer class is not youngster or cue ball: do not use an attack that only gives a status if the opponent already has a status.

They also have a preference for super effective moves (with some bugs because gen1 is held together by bugs) and will not pick a "not very effective" move if there's no alternative.

There's also some cases where (for story reasons generally) a specific attack is chosen, this overrides regular selection and can lead to doing impossible things (i.e. a 2-turn move like fly starting, and then a different move happening).

Basically the AI does no planning ahead and just looks at the current state, it's not a very good AI because, well it's a game. You don't want a great AI opponent because then you'd lose far too often.

Source: http://wiki.pokemonspeedruns.com/index.php/Pok%C3%A9mon_Red/Blue/Yellow_Trainer_AI