From Glitch City Laboratories
|Please note that this glitch only exists in the Japanese versions of the game, or is otherwise a glitch from a Pokémon game which was only released in Japan.
A Kadabra, using Trick to swap Mail with a Numel's Rawst Berry, as part of the Mail Trick glitch
The Mail Trick glitch, refers to in potential, an undesirable glitch regarding a Pokémon holding Mail and a Pokémon knowing the move Trick. This glitch only existed within the Japanese versions of Pokémon Ruby and Sapphire. If a player's Pokémon was holding a Mail item and the player, or the opponent's Pokémon used the move Trick, if the opponent Pokémon was also holding an item, the game would mention that the opponent has received the player's Mail item and that the player has received the opponent's held item, although at the end of the battle the player would still be holding the Mail.
After taking advantage of the problem, if the player then writes a message to the mail item and attempts to replace the item with a different one from his or her bag, its item quantity will decrease, although the player's Pokémon will not be holding it and instead, will still be holding the Mail item that it had before.
This glitch was fixed in later versions and in the English version of Pokémon Ruby and Sapphire, as these games restricted the player or the opponent from using the move Trick if the other Pokémon was holding a Mail item.
- Access to an opponent which holds an item; ideally a wild Pokémon which has a 100% chance of holding one, such as Numel.
- Any Mail item in possession of the player.
- To extend the glitch, the player will require another item that his or her Pokémon can hold.
- To have received at least one Pokémon.
- Attach a mail item to a Pokémon, preferably with that Pokémon knowing the move Trick.
- Enter a wild battle, or trainer battle and ensure that the opponent is holding an item. If the player's Pokémon does not know the move Trick, ensure that the opponent does.
- If step two fails, return to step one and try again.
- Use the move Trick, or have the opponent use it, such that the opponent would receive a piece of Mail, and that the user would receive the enemy Pokémon's held item.
- Finish the battle by defeating the opponent or running away, ensuring that Trick is not used again.
- The player's Pokémon will still be holding the older piece of Mail, despite the fact that under the developer's intentions it would have gone to the opponent.
- After performing the steps mentioned above, if the player then attaches a message to the relevant Pokémon's mail and performs the steps again; the oversight will persist with an additional consequence if the player attached another item to replace it. This would lower the item's quantity as normal, although the old held item would not have been replaced with the new one. This can be repeated for the amount of times the glitch was extended, providing the player attached a new message to the Mail each time.
-  A Youtube video demonstration by 0xwas