Focus Punch "tightens" and attacks in the same turn. This is how it goes:can someone explain how people are using focus punch on the same turn it's cast. Whats happening is I switch and they tighten. my pokemon comes out they attack me. that's moving twice in the same exact turn. this is an example of what im talking about http://replay.pokemonshowdown.com/ou-116933422
Turn 1:
If the opponent used focus punch here, it ALWAYS states "x is tightening it's focus" before protect, switching, mega evolving, priority moves, etc. This line has like +7 or +8 priority, highest in the game.
If you attack, the focus punch is cancelled. If you don't, the focus punch happens. It's that simple. When you switch, you don't attack, so focus punch happens. The focus puncher needs to be directly hit for Focus Punch to be cancelled, that's why substitute is often used with the move.