In Pokemon Ash Gray, you can find the following to evolve Pokemon:
* Evolution Stones: These are common items found in various locations, like:
* Fire Stone: Located in the Burned Tower (after defeating the Rocket Grunt).
* Thunder Stone: Can be found in the Rock Tunnel (after defeating the Rocket Grunt).
* Water Stone: Found on Cinnabar Island.
* Leaf Stone: Can be found in the Viridian Forest.
* Trading: Some Pokemon can only evolve by trading with another player.
* Leveling Up: Some Pokemon evolve simply by reaching a certain level.
To be sure about how to get the specific evolution items you need for a Pokemon in Ash Gray, I recommend using a Pokemon Ash Gray walkthrough guide or checking a Pokemon Ash Gray wiki online.
Let me know if you have any other questions!