From Bulbapedia, the community-driven Pokémon encyclopedia.
A linked move is a technique in the Pokémon Mystery Dungeon series that allows more than one move to be used in one turn.
Linked moves can be created by buying the services of Gulpin in the first game's Pokémon Square or Electivire in the second game's Treasure Town. These shops charge 150 Poké (first series) or 500 Poké (second series) for the service. Linked moves can also be created by using the functions of a Link Box within a dungeon.
Whenever moves are linked, the moves are executed in order from top to bottom within the link. For example, if the moves Heat Wave and Sweet Scent were linked in that order and used in a large room, the enemies in the room would first be damaged and then survivors would have their evasion lowered. Link them in the opposite order and the evasion drop would come before the damage. Moves are executed on the same turn, so the opponent cannot react between moves.
It is possible to link two, three, or all four moves in a Pokémon's lineup together in this way. However, if even one move in a link runs out of PP, the entire link is broken and the moves are no longer linked. Moves can also be delinked manually at any time. Moves which require more than one turn (e.g. with a recharge turn) to execute cannot be linked.
If the final hitpoint of a Pokémon yielding experience is depleted by a linked move, experience earned will be slightly boosted.