I've played both Ryu and Pixel and beat the final boss on my first try with both of them, Pixel only at 75% upgrades. Bit took a second try after upgrading a bit, but I won with full life. Just gotta be patient and play smart: go counter/defense if you're in threat of being smacked, go attack/magic if his defenses are down, otherwise charge up on energy/life/rage. You'll last long enough that eventually you'll get enough bombs and x5's to get him down.
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 "BioGems"){kind=icon}