As both of these series’ main characters are from the same guy, it’s only fitting that they fight each other. Haiji can manipulate gravity to a powerful degree but Asta’s already fought someone like that before. Haiji will not be able to make Asta bend to his will. Asta’s anti magic is just too powerful and in addition he has several super forms at the ready. Haiji’s going to be on the defensive and will quickly be defeated. Asta wins.
This is a battle of gravity fighters. Kat uses gravity to amp up her physical abilities and move at super speeds while Haiji usually uses it more for projectiles. Although Haiji can use it physically as well and was even able to lift an entire chunk of a building. He just seems to be able to use it at a much higher level than what we’ve seen Kat do. While she may be able to put up a decent fight at first, the match is over once Haiji uses his Hungry Joker form. Haiji (Hungry Joker) wins.