Gym training analysis

If I have a 15/0/0 Pokemon at 300 cp, it will have higher attack than a Pokemon of the same breed at 15/15/15 and 300cp, correct? Whilst it's Iv is 33%, being at the same cp means it would be at a higher level to hit the 300cp. As the majority of its cp is coming from attack, would this make this Pokemon more effective at training a gym with a 600cp Pokemon in the first slot?

Basically, same cp, so both would get the extra prestige bonus. However as it would have its stats skewed towards attack, it would be faster at destroying the first Pokemon in the list. Does this mean a Pokemon with a low Iv is actually still of use?