Tesla and Nostradamus' fighting styles will hopefully live up to Jack's.
Sakata Kintoki is the super kid, right?
Another question: Who do you wish would have been included?
I know the authors of the manga are Japanese, but I wish they hadn't included more than 3 fighters from Japan and I believe Kojiro should have been the only swordsman/samurai included. After all, he should be second only to Musashi in terms of famous samurai (and this manga really drew a new light on Kojiro, made me respect him a helluva lot more) while I didn't even know who Raiden was (would rather have seen The Great Gama if we talk about wrestlers, tbh) and the prodigious Okita Souji will be difficult to be emotionally invested in after we have seen Kojiro's trial(s), so I'd rather see a Japanse hand-to-hand martial artist like Morihei Ueshiba (founder of Aikido).
This is also true with Emperor Qin Shi Huang. I think having King Leonidas alone would have been enough to represent "ruling nobility." China is a treasure of great martial artists and the exclusion of Chinese barehanded martial artists was an honest surprise for me. The founder of Tai Chi, a famous Shaolin monk, and even a more contemporary martial artist like Ip Man would have been more interesting, imo.