My league has started to introduce unlimited in our for-fun tournaments once a month, and this question came up. If there is a Mr. Mime with Eviolite attached to it, which effect takes place first? I told him I'd come back with an official ruling, but my initial ruling is that they're simultaneous effects and you choose the order. For example, if someone deals 40 damage with an attack, he can choose whether the eviolite reduces the damage to 20 (thus making the attack go through) or he can choose for the power to take priority and completely negate the damage.
Basically, are they simultaneous effects? Or do Pokemon Power effects and Tool effects fall in different steps of damage application?