Lucas isn't actually all-that good for boss battles IMO. Tabuu can get too high in the air for PK fire to reach, meaning he has to approach slowly by foot. His aerials can't be landed in rapid succession either.
I'm still above average with him, though.
It's a chain, not a whip. :P Tabuu's trophy calls it those things Chains of Light, thus they're chains. ... Even though they do look like a spiked whip. Chains of Light sounds better anyways.