When a Pokémon with Forewarn is sent out to battle it alerts the user of the opponent's attack with the highest Base Power. If there is a tie in the Pokémon's movepool for the highest Base Power it will randomly select one of the attacks. In a double battle it will only select the highest Base Power attack from one of the opponent's Pokemon.
Any attack without a Base Power is assigned one as follows:
|160||Fissure, Guillotine, Horn Drill and Sheer Cold|
|120||Counter, Metal Burst and Mirror Coat|
|80||Crush Grip, Dragon Rage, Endeavor, Flail, Frustration, Grass Knot, Gyro Ball, Hidden Power, Low Kick, Natural Gift, Night Shade, Psywave, Return, Reversal, Seismic Toss, Sonicboom, Trump Card and Wring Out|
|0||All other attacks without a fixed Base Power|
Note that these Base Powers have no implication on the amount of damage done by that attack, they are simply a way Forewarn uses to rank the Base Powers of all of the opponent's attacks.
Forewarn doesn't have an effect in the overworld.
Pokémon With Forecast