Easiest way to get perfect hits is to use power attacks, since then you just have to mash the screen, not get your timing right.

The best way that I've found to do 10 power attacks is to take grim reaper eddie and two golden skulls (the ones that are supposed to be only good for selling). The golden skull's power ability costs 1 and gives you a lot in return. I do both skulls first, which fills up my power. Then I do grim reapers "Death Grip" power ability (looks like a skeleton hand). That freezes everyone and gives you an extra turn. So I do it again. Then use a basic attack that only hits one person. Most likely everyone will still be frozen and you can do it over again.

To make things a bit easier, I've got celestial on one of the golden skulls, which keeps them alive for a turn if not all the bad guys get frozen. And I fury to bring them back if they die.

Same team works for "9 basic attacks" too, since the skulls basic attacks do very little damage, you have time to get a lot of hits in.