Pokemon Mystery Dungeon Red (GBA) came out simultaneously with Mystery Dungeon Blue (DS) back in 2006 and started the mystery dungeon series (a rougue-lite-like?).
Embark on a great adventure as a Pokemon and solve the Mystery of the world and how you came into this world! (They did Isekai before it became mainstream).
From memory, it was a really fun game with a lot of Pokemon to collect. Plenty of Pokemon to recruit and a lot of Legendary Pokemon to meet on your journey.
Features the first 3 generations of Pokemon - Kento, Johto and Hoenn Regions.
Note: Your starting Pokemon is determined by a quiz at the start (if you don't like the random-ness, look for a guide to select). Your buddy is selectable buy from a smaller list.
Actual official description:
What if you woke up one day as a Pokémon?
All of a sudden, you've found yourself in a strange world, where you can speak and interact with other Pokémon. The adventure begins when you and your partner Pokémon set out on rescue missions in a world ravaged by natural disasters. But what is your true purpose and destiny in this Pokémon world? That's the REAL mystery…
An amazing game. I remember playing it on my DS Lite…