The Mail and Trick glitches are glitches only found in the Japanese versions of Pokémon Ruby and Sapphire.
In Japanese Ruby and Sapphire, it's possible for the user to swap their Mail for an item using the move Trick.
After fleeing from battle after exchanging Mail for an item, the item is replaced with what it is supposed to be, but with the Mail icon instead of the regular item icon.
The item has an 'item' option instead of a 'Mail' option, and is said to be the correct item on the Pokémon's summary screen. It can be taken for the correct item if there is room in the pocket.
Ideal wild Pokémon for the glitches
The Numel on Route 112 always hold Rawst Berries, so performing the glitch with one is guaranteed. They are also pretty common. To get to Route 112 quickly, go east of Lavaridge Town down the ledges.
Be aware that a Numel's Ember can burn you though, causing you to lose your Rawst Berry, because it heals burns.
Steps for the first glitch
- Level a Kadabra (obtainable by evolving Abra or through trade) up to level 43 so that it learns Trick.
- Give it a Mail item (Orange Mail is available from Petalburg City).
- Fly to Lavaridge Town then go east to get to Route 112, where you should jump off the ledges and enter the grass.
- Encounter a wild Numel (flee if you don't), then use Trick on it. This way you'll swap your mail for the Rawst Berry.
You can also use the glitch for other Pokemon.
This trick is known as item growth (Japanese: アイテム増殖).
After performing the steps for the first part of the glitch, repeat steps 2. and 4. five times by giving Kadabra a new Mail and taking a Rawst Berry in return. You must not have 999 Rawst Berries or you'll get a message that the bag is full.
Give Kadabra Mail once more and the glitch occurs:
You will not have to give Mail a message when giving it as a held item.
You will receive another Rawst Berry from out of nowhere (only five Numels should have been encountered, but you can obtain more than five Rawst Berries). This can be repeated many times (possibly infinitely) and you don't have to use the same Mail. You can't give another piece of Mail if the number of Rawst Berries caps at 999, though.
There's also a third glitch that allows you to walk on water. You can see that here: