Different fighting styles. Kat was Luffy's best version and fight the same, he had to learn FS to win.
Queen is a bad matchup for Sanji, it's just going to be dodging bullets and beams then blitz kick. He also counters the Ice Plague.
I actually made a theory way back on Queen, and I hope Oda has at least some similar idea to it...
My theory states that Queen can transform his fat body into a more muscular thinner looking more agile form.. and it will be LOVED by most fans that even guys who wants to face King for his cool design... will want Queen instead...
My evidence for the theory was Queens introduction music “the zoom zoom zoom song”
He specifically said “I look fat BUT it’s ALL muscles... if I get thinner.. I will be too popular.. so I choose to look fat”
And with people who have techniques like Lao G who stored his muscles... or semei kikan like with Komadoru In CP9... it’s not gonna be the first time for Oda to draw a very fat guy to suddenly have a superman like physique... like a greek god! Lol
it’s a farfecthed theory but could really have the fans very overjoyed about the tranformation..