As a Pokémon expert, I can tell you that Wartortle evolves from Squirtle starting at level 16. To further evolve Wartortle into its final form, Blastoise, it requires a special item called the Water Stone. Here's the step-by-step process:

1. First, you need to have a Wartortle, which is the second stage evolution of Squirtle.
2. Make sure your Wartortle is in your party when you're ready to evolve it.
3. Obtain a Water Stone. This is a special kind of evolutionary stone that can be found in various locations within the Pokémon games, or it can be purchased from specific in-game stores.
4. Use the Water Stone on your Wartortle. The command to use the item will vary depending on the game version you're playing.
5. Once the Water Stone is used, your Wartortle will evolve into Blastoise.

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Wartortle (Japanese: ����`�� Kameil) is a Water-type Pok��mon introduced in Generation I. It evolves from Squirtle starting at level 16 and evolves into Blastoise starting at level 36.read more >>