monado arts charge up by me landing other attacks. once it finishes charging, i can use one. then i have to charge more energy to use another monado art. regular arts such as back slash just recharge over time. it's really a cooldown type of deal. i still have to wait a minute or two to reuse an art, but i can use a different art in the meantime. my monado arts are pretty much my exclusive attacks. arts don't take magic at all, especially ones that are physical attacks such as back slash. my magic is mostly used to aid allies and mess with enemies while my arts are my main form of unique attacks.
About volt switch and u-turn, maybe you can switch pokemon that you are megred with. For example, i can switch from a victini to a greninja without any delay or problems except entry hazards and pursuit. As for getting hit by something like dragon tail, maybe it can cancel the merge and split you and your pokemon apart.