One Piece would have less sales. Neither his personality nor his design is nearly as badass as Zoro, having a character like Zoro right off the bat in a duo with Luffy, is one of the pillars of One Piece's success imo. As for power wise, Oda would bend arcs in his favour, he would now have MC plot protection at all times, so he would survive any situation Zoro survived, and thrive in any situation Zoro thrived in.
Overall it's a massive downgrade, Killer's design and style is not suited for a deuteragonist of a shonen manga, even in verse it would make for less badass moments given his personality. Things would be a bit too organized with Killer around, what makes the SHs stand out from other crews is how chaotic they are.
Overall it's a massive downgrade, Killer's design and style is not suited for a deuteragonist of a shonen manga, even in verse it would make for less badass moments given his personality. Things would be a bit too organized with Killer around, what makes the SHs stand out from other crews is how chaotic they are.