How do you get into the poison chambers in Pokemon ash gray?

You can't actually get into the Poison Chambers in Pokemon Ash Gray. This is because the Poison Chambers were a feature in the fan-made game Pokemon Gaia, not Pokemon Ash Gray.

In Pokemon Ash Gray, the Poison Chambers, and any mention of them, don't exist. If you're trying to find them, you may be mixing up the games.

If you're playing Pokemon Ash Gray and are looking for a specific location, you can always refer to a walkthrough or guide for the game.