Yup. You can repeatedly Sonic Blade your way through entire boss fights (and Heartless battles if they're all ground) w/o getting hit a single time. After I got Lethal Flame that became my go-to. I literally beat Marluxia in Proud mode with a fat stack of Lethal Flame's, three Heals, Riku's card, Marluxia's card, and an ?Elixer? (w/e gives you back attack and magic cards instantly) or two.
You use two Lethal Frames correctly timed to take out his Nobody robot's blades. Then you use your Stop spells to cancel anything he throws at you, whack him a few, heal and dodge as needed. This part is actually harder than the second, but it's worth it because the deck is insane.
For the second half of the final battle you just run up to him, apply Riku's card, Lethal Frame until you run out of cards (you can set up the next three cards for another Lethal Flame before the first one stops hitting, it's silly, he doesn't stand a chance, literally just mash Triangle), use the Elixer and Marluxia card at this point, heal if needed, run back up to him and f*** his face. GG.