10. Tanjiro Kamado VS Jonatha Joestar (Demon Slayer VS JoJo's Bizarre Adventure)
Connection: Both are kind-hearted fighters who slay the undead with abilities related to the sun (Water Breathing and Hamon). Both wanted to save their kin (Nezuko and Dio Brando) from their undead status and bore a mark relating to their bloodline.
Who wins IMO: Jonathan probably. Tanjiro may be more skilled than Jonathan, but Jonathan can react to lightspeed compared to Tanjiro's lightning. Plus his Hamon can directly affect his organs which Tanjiro uses his Water Breathing abilities from and heal Jonathan on the fly while only needing a single breath to recharge.
9. King K. Rool VS Blackbeard
Connections: Both are overweight, greedy pirate kings who led a pirate crew and are the main nemesis for the protagonists of their series (Donkey Kong and Monkey D. Luffy).
Who wins IMO: There have been people scaling Rool to Mario and the main cast but it's a shaky scaling and Blackbeard has FTL scaling over King K Rool's and even using DK's moon feat, both have Gigaton strength and Country level feats. Unless the Mario scaling is proven to be true, Imma go with Blackbeard for now.
8. Akame VS Killua Zoldyck (Akame Ga Kill! VS Hunter x Hunter)
Both are assassins created at a young age who have siblings from a bloodline of killing. Both also have a form that increase their speed (Godspeed and Ennoodzuno)