Focus Punch is a decreased priority move. The user of Focus Punch will charge up during the beginning of the turn it is executed, then attack at the end unless it is hit by another Pokémon's attack before launching its own; in which case it will lose its focus and be unable to attack that round.
In Mystery Dungeon series, Focus Punch instead has a charge-up turn (akin to Skull Bash, Sky Attack, et cetera), and can hit even when the user is hit during the turn of charge-up, unless the user is inflicted with Paralysis.
Focus Punch has the highest base power of any Template:Type2 move.
Focus Punch will not cause the user to flinch if the user is hit by Revenge or Avalanche. These are the only two attacks that will go after Focus Punch.
A minor glitch will cause the user of Focus Punch to prepare to use it, but not execute the attack. To do this, enter any double battle with a Pokémon that knows Focus Punch in the first slot. Order it to use Focus Punch, then cancel the order and use an item instead. Once an order is issued to the second Pokémon, the first will prepare to use Focus Punch, and the animation for this will be performed. However, since the order was canceled, Focus Punch won't execute and the user will not attack in spite of preparing to use the move.