If my opponent uses Exeggutor’s “Head Crack” attack, then my Active Pokemon retreats for another Pokemon that has the same attack name that was blocked, can my new Pokemon use that attack or is it blocked?
Head Crack places the effect on your Pokemon that was Active when attacked, so when that Pokemon is benched the effect of Head Crack ends.
Source: Vivid Voltage FAQ (2020-10-31), TPCi Rules Team (2020-11-12)