Yes, it applies for some moves if used consecutively. It technically applies to every Pokemon as wll
- If you use a move with a a base power of greater than 50, and then run out of PP and are forced to Struggle
- All Z-moves and most Max Moves are stronger than the original move, but when you use up the Z-move/run out of Dynamax turns, the original move is usually weaker.
Moves that literally stale
Moves like Leaf Storm, Superpower, Draco Meteor, Draco Meteor, and Psycho Boost get weaker every time they are used, if you stay in. Outside of that, no.