Interesting.
My vibes were Dragon = Koby in Marineford, and Luffy = Kaido.
Koby was too weak to help fight, but, risked his life to save lives. Dragon was too weak to help fight, but risked his life to save the twins. Keep in mind he knows they are CDs, too: Dragon is just a good Soul.
Kaido IS strong, like Luffy in Marineford, but just can't hang with the top tiers, but keeps trying, anyway. Eventually, Kaido gets overrun, and needs a stronger pirate, who isn't quite in their prime yet (Linlin = Jinbe) to save them from the island.
I think Koby is replacing Garp as this series' Haki-man with bare fists.