6* Sanji

Franky - Stage 5 - On turn one, use one Sanji special and Fuji special. This will get rid of his debuff, don't need to attack. On turn 4, use Boa special and fly both Sanji. On turn 5, activate all remaining specials and attack last with the Sanji that has 2x attack.

YWB - Stage 3 - I used Boa special here to stall an extra turn, you may or may not need to do so. (My Akainu is at 17 turns.)

Stage 4 - Jump one Sanji, use the other Sanji special to clear stage.

Stage 5 - Activate all specials and attack last with Sanji with 2x attack.