Izou

WHY THE HELL WOULD IZO USE GUNS EVEN THOUGH HE'S FROM WANO?!

Ya'll remember the time that Whitebeard (or I guess "Whitey-Chan") let Oden join after he survives the whole hanging on to the floatie (or was it the anchor?) ordeal, and then Izo went "curse you Newgate! What have you done to my Master?! You will pay for this someday!!!", so during his early days as a part of the Whitebeard Pirates, he tried to kill Whitebeard, but failed, because he's Whitebeard and his sword would already be shattered, so he tried to use guns to kill Whitebeard, but luckily, he grew attached to the Whitebeard Pirates ;)

Izo is Kikunojo's brother. Since childhood, both had a fondness of dressing as a woman (as shown in the image of Izo as a child). He was the Red Scabbard with makeup that was in the flashback about the encounter with Yasuie (the hairstyle is similar, he even has a hanging hair).

He accompanied Oden on his trip as members of the Whitebeard Pirates. Oden was the commander of the 16th division, but when Oden joined the Roger Pirates, Izo took his place. Therefore, Izo was replaced in the Red Scabbards group by Kiku.

(just speculation, I can become wrong)