"When held by the team leader, this hold item makes it easier to recruit defeated Pokémon into the rescue team."
In-game description for Red and Blue Rescue Team.
"A team-leader held item that makes it easier for the leader to recruit defeated Pokémon into the team."
In-game description for Explorers of Time, Darkness, and Sky.
In both Pokémon Mystery Dungeon: Red and Blue Rescue Team and Explorers of Time, Darkness, and Sky, the Friend Bow adds 10% to the recruitment rate of recruitable Pokémon. In Rescue Team, a Friend Bow can be found on Mt. Faraway and as merchandise in shops within Joyous Tower. In Explorers, Friend Bows can be bought from Kecleon in Zero Isle North and found in the Marine Resort.
In Pokémon Mystery Dungeon: Gates To Infinity, the Friend Bow's only known location is in Pika Land, floor 5 and up. It is not known to be found in any Kecleon shops.