Yusuke is the wielder of the mini kamehameha titled the Spirit Gun. It’s a massive beam that can shatter a planet with incredible ease. He also has 3 super versions of The Spirit Gun which are, Demon Gun, Spirit Wave, and Mega spirit Gun. However Hiei has been fighting thugs since he was an infant and has tremendous power. Hiei has The Dragon of Darkness Flame. He also has a dragon super form. His swordsman ship and power far surpasses Yusuke’s, Hiei wins
But now Yusuke’s a better fighter. Yusuke wins.
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Yusuke’s spirit gun has never been shown to destroy planets. That would be silly
I’d say he’s a casual planet buster. By the end his Spirit Guns are pretty much as big as Kamehamehas.