Where can you get the Warp Pad in Pokemon AshGray?

You can't get a Warp Pad in Pokemon AshGray.

AshGray is a fan-made ROM hack of Pokemon FireRed/LeafGreen, and it doesn't introduce the Warp Pad item. The Warp Pad was introduced in Pokemon Ruby/Sapphire and later games.

Therefore, you won't find the Warp Pad in AshGray. You will still be able to use the standard methods of transportation in the game, such as running, biking, flying, and using HM01 (Cut).