An opponent in versus mode used Charizard EX's Combustion Blast against me two turns in a row, even though that attack explicitly states that: "This Pokemon can't use Combustion Blast during your next turn".
Pretty sure it was the Illus. Planeta 12/116 card. (Sadly, I did not record the fight).
The way he did it was to use a Float stone on the Charizard EX in combination with Guzma, in order to retreat the Charizard EX that had just attacked using Combustion Blast the turn before, and then switch the Charizard EX back in using Guzma. To my complete surprise, this allowed him to use Combustion Blast again for a second turn in a row!
This, to my mind, must be categorized as an unlawful exploit - and hence a bug.