Hellsweep's the best 50/50 in the game, the only thing kazuya's weak at are people who have balls the size of melons who just keeps doing df f df f since both ewgf and hellsweep (his 2 best tools) can be crouched and hellsweep can be down parried.

Just keep playing ang get familiar with match ups and learn how to punish characters you face a lot's most used moves, preferably characters who are being used a lot, like Paul, Jin, Kazuya, Hwoarang, etc etc.