There are over 300 Pokemon in Pokemon Brilliant Diamond and Shining Pearl. Of course, you won't be able to find all of these Pokemon right away. You have to do some work. Among the Pokemon in the remakes, you can find Treeko, Torchic and Mudkip. These Gen-III starters are yours, but where do you find them?
Before you can find these Pokemon, you must first unlock the national Pokedex. To unlock the national Pokedex, you will need to complete the game. This means that you must defeat the Elite Four and become the champion of Sinnoh. It's not all. You also need to see all 150 Sinnoh Pokemon to complete the standard Pokedex. Once that's done, go back to Professor Rowan in Sandgem Town and he'll give you the national Pokedex.
With your new Pokedex in hand, you can now discover new types of Pokemon. For Torchic, Treeko, and Mudkip, you'll need to go underground. Each of these Pokemon can only be found in specific Pokemon Hideaways in the Grand Underground.
Here are the biomes where you can find these Pokemon:
- Torchic: Volcanic Cavern, Sandsear Cavern, Typhlo Cavern
- Treeko: Prairie Cave, Riverside Cave, Still Water Cave, Sunlit Cave
- Mudkip: Fountain Cave, Riverside Cave, Calm Water Cave
As with any other Pokemon in hiding places, if you don't see the desired Pokemon when you enter, exit and re-enter. This will reset the spawns and hopefully you will get the Pokemon you are looking for.