Very new Pokémon tcg player (father trying to learn the rules here).
I wonder if the effects of an attack are mandatory or optional. Like I have a Alolan Sandslash whose Smash Turn attack (requires 3 energies, deals 50 points) says to switch with a benched Pokémon afterward. This can be: very annoying if I am forced to switch with a base or otherwise weak Pokémon or it can be helpful if by switching I remove some condition or it can be impossible if I don't have benched Pokémon.
So, is it mandatory or optional? What if it is impossible to fulfil, can I attack nonetheless?