In Red Rescue Team and Blue Rescue Team, if a newly-recruited Pokémon—a recruit who has never cleared or warped out of a dungeon—or the team's leader faints before making it out of the dungeon, it will leave the party permanently. Dungeons consisting of multiple parts—such as Mt. Thunder—will count reaching a checkpoint as making it out.
The games contain items that increase the chance of Pokémon asking to be recruited. These are important as the base recruit rate of certain Pokémon, most notably Kecleon, is below zero.
In addition to the prospective recruit having an effective recruit rate higher than zero, there are several other prerequisites for recruiting a certain Pokémon to be possible:
In the first two games, offers will only be made if there is space in the current party. In the sequels, this requirement was removed, instead excess members simply warp out of the dungeon. In Explorers of Sky and Gates to Infinity, players can choose if they want to send home the recruited Pokémon or not.
The team leader must deal the finishing blow that causes the enemy to faint. Status conditions such as poisoned, even if inflicted by the team leader do not count.
The enemy must be adjacent to the team leader when the finishing blow is delivered. However, Pokémon that are not immediately recruited when the final blow is dealt, but after a short cutscene (many Legendary Pokémon for instance), are an exception to this rule.
Some Pokémon, such as Omastar in Brine Cave, are unrecruitable. In addition, many boss legendary Pokémon cannot be recruited on the first visit. In Red Rescue Team and Blue Rescue Team, all but nine fully-evolved Pokémon cannot be recruited and have to be acquired via evolving.
The player must have bought the Friend Area that a prospective team member belongs to. This means that some Pokémon cannot be recruited until the post-game, because their Friend Areas aren't available for purchase until then. This is not the case for some legendary Pokémon such as Kyogre, whose Friend Areas cannot be bought; instead, their Friend Areas are unlocked after they are recruited.
An amber liquid that sparkles like crystal-clear tears, rumored to be the most precious of even the rarest treasures. When held by the team leader, it is easier to recruit defeated Pokémon to the team.
A legendary mask, rumored to be from a long-lost civilization. It has a beautiful glow that stirs up the emotions of all who see it. When held by the team leader, it is easier to recruit defeated Pokémon to the team.
In Red and Blue Rescue Teams, the only such item to increase recruitment is the Friend Bow. When held by the leading Pokémon, it raises the recruitment rate by 10%. The bow is located behind a door needing a key to open on floor 30 of Mt. Faraway. Further Friend Bows can be purchased from Kecleon shops in Joyous Tower. In Explorers of Time and Darkness, the Friend Bow's effectiveness is reduced to 5%, but is supplemented with a number of other items. It can still be bought from Kecleon Shops in Zero Isle North, and in Explorers of Sky, the Friend Bow is able to be won as a prize item from the Recycle Shop in Spinda's Café.
Introduced in Explorers of Time and Darkness, the Amber Tear can be found located on floor B40F of Zero Isle West, or given as a reward for a mission in search of the Amber Tear. It is essentially a 'mid-tier' recruitment boosting item, with the ability to boost the user's recruitment rate by 15%.
The Golden Mask, also introduced Pokémon Mystery Dungeon: Explorers of Time and Darkness, has the highest boost to the recruitment rate of any item, at 20.1%. It should be noted that this boost is necessary to recruit Kecleon. It can be found on floor B75 of Zero Isle North, or given as a reward for a mission in search of the Golden Mask.
In Pokémon Mystery Dungeon: Gates to Infinity, a Friend Gift raises the recruitment rate for Pokémon of one particular type. They are given to the Pokémon and the Pokémon will decide whether to accept the Friend Gift and join the team or not. The Friend Gift is not lost from the items list if it is rejected. Friend Gifts do not work on evolved Pokémon.
There are also Friend Gifts for specific Pokémon.
Friend Gifts are given as prizes after completing missions. They can be bought at Gift Shop. They are also available with specific passwords.