* Pokémon Ruby: This is a game in the Pokémon series, where you capture Pokémon to train and battle them.
* Rescue Rangers: This is a Disney franchise featuring a team of mice who solve mysteries.
It's likely you're thinking of a fan-made game or a mod that combines elements of both franchises. If you can provide more information about the game you're talking about, I might be able to help you find information on how to catch Pokémon within that specific context.