Challenge "Cover change 1 time(s)" what is this,

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The quest cover change 1 time(s)
How i have to do?

Cover is when the enemy does an attack like a ki blast or strike card on your character but last minute you switch characters and pushes the other out of the way. Some characters have great covers like ssg vegeta,ssj vegito and cell that will counter or even full on dodge your opponent. Some can even dodge rr