Avoid dying - Save the game just before you go on a rescue. If you die, immediately turn off the power to your DS. Once you turn it back on, it will be as if it never happened. This is useful when going on long missions like Articuno, Groudon, and Rayquaza. It is very hard to complete the second part of some missions if you lose most of your items.
Bonus dungeons - Successfully complete the game to unlock the Desert Region, Waterfall Pond, and Wyvern Hill dungeons.
Evolution Stones - Some Pokemon require the use of items to evolve, such as stones or ribbons. Here are the locations of those items:
Evolving - After defeating Rayquaza, you can go to a cave next to the Wishcash Pond. Your partner will ask if it can leave you and go to its Friend Area. Select "Yes" and you can enter the cave. Inside, a stone will ask if you want to evolve. You can evolve others by going to their Friend Area and selecting "Become Leader".
Passwords - At the main menu, go to Wonder Mail and enter one of the following passwords to unlock the corresponding bonus:
Ranks - Get the indicated number of Rescue points to achieve the corresponding rank:
Recruiting Mewtwo - Mewtwo is at Western Cavern on the 99th floor. You can unlock it by recruiting all the Legendary Pokemon before him including Ho-Oh, Entei, Raikou, Suicune, Zapdos, Articuno, Moltres, Kyogre, and Groudon. Western Cavern is a difficult dungeon, and you will be able to recruit almost all of the fully evolved forms of the nine starting Pokemon. To recruit Mewtwo you must defeat him with only one Pokemon in your team. When you get to floor 98, dismiss two of them and prepare for a battle. Mewtwo has about 900 HP.
Special missions - At the main menu, go to Wonder Mail and enter one of the following passwords, then complete the given mission to unlock the corresponding bonus:
Statues - Successfully complete the indicated task to get the corresponding statue:
Team base - After you defeat the Mankey Gang in Uproar Forest, Jumpluff will give you one Peeled Chestnut. Give it to the Mankey Gang to pay for construction of your team base. You only need two more Chestnuts from Uproar Forest. You usually cannot find them until Floors 7 or 8. Your Pokemon peels a Chestnut to make it a Peeled Chestnut. Once the construction is complete, your base will look like your Pokemon's head.