Here’s my headcannon matchups and speculation
Luffy vs Blackbeard (rivals)
Zoro vs Shiryu (2nd strongest/powerful swordsmen)
Nami vs Devon (leading ladies/Catarina hunts beautiful women and Nami takes pride in her beauty)
Usopp vs Augur (Sniper duel)
Chopper vs Doc Q (only matchup i’m purely looking at roles)
Sanji vs Pizarro (north blue prince vs corrupt north blue king)
Franky vs Burgess (Franky can box, he can wrestle, he also exudes macho characteristics, Burgess is clearly luchador inspired w machismo energy)
Jinbe vs Vasco Shot (pure headcannon I think Vasco is a fishman and yeah I’m matching them off of race lol)
Robin vs San Juan Wolf (power users that can alter their size)
Brook vs Lafitte (very similar in design, tall/slender entertainer style, canes, laffite might have an angel fruit based on those wings, both have hypnotic ability, demon sheriff vs soul king, come off as two sides of the same coin)
speculation pick for each crew’s final member:
Yamato vs Weevil (yonko children, brute strength, both self styled as people they admire, not Oden not Whitebeard 2.0 whether he’s actually his son or not)