Max Strike does damage to a target and lowers the Speed of all opponents by one stage. Its power and whether it is a special or physical move depends on the move it is based on.
If Max Strike is used with Multi-Attack or Techno Blast as its base move while the user is holding a Memory or a Drive, respectively, Max Strike turns into the Max Move of the type corresponding to the type of Memory or Drive held by the user.
If Max Strike is used during weather with Weather Ball as its base move, it turns into the Max Move of the type corresponding to the type Weather Ball would be in that weather. In a similar way, if Max Strike is used during terrain with Terrain Pulse as its base move, it turns into the Max Move of the type corresponding to the type Terrain Pulse would be in that terrain.
If Max Strike is used by a Pokémon with Aerilate, Galvanize, Pixilate, or Refrigerate, it turns into the Max Move of the type corresponding to the Pokémon's Ability.
Dynamax Gyarados strikes its tail into the ground, sending sparks of energy across the battlefield and towards the opponent. When the sparks reach the opponent, the ground underneath them explodes.
Gigantamax Pikachu jumps into the air, creating yellow glowing cracks on the ground as it lands. The cracks spread toward the opponent, and as they reach them, a burst of yellow energy erupts from the ground underneath the opponent.
Gigantamax Machamp stomps the ground with one of its feet, creating glowing cracks on the ground underneath the opponent. A burst of energy then erupts from the cracks.