If you are not using the Attack stat there is absolutely no reason to use a perfect IV. I don't know why everyone is so hyped to have 6IV but if you are using pokémon that will only use it's Attack or Special Attack I see no reason for a 6IV. If you are a mixed attacker I can understand. Some pokémon need different IV spread like Ferrothorn to deal more damage with Gyro Ball. Also if you are breeding for a Hidden Power it's not a necessity to have perfect 6IV unless you want Dark.
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IGN: Rob