What does metal powder do on Pokemon indigo?

There is no mention of "metal powder" in the context of Pokemon Indigo. This is likely a misunderstanding or a reference to something outside of the Pokemon anime.

Here's why:

* Pokemon Indigo refers to the anime series, which is based on the Pokemon video game series.

* Metal Powder is an item in the Pokemon games that increases the power of a Pokemon's physical attacks.

It's possible you are thinking of a different context, such as a fan-made story or a different media that uses the Pokemon franchise.

If you can provide more details about what you're referring to, I can help you further.