Mad Max can't bring himself to defeat
Caesar.
O'Brien suffers a tragic mishap just before fighting
Rincewind.
Darkwing Duck gets dangerous on Shaq.
Inframan (The Super Inframan)
Seems to be Ultraman by way of China, up to and including the "grow to kaiju size" power. Here is the text of the "Heroes Wiki" article on Inframan -- interpret it how you will.
Personality
Infaman is a determinable superhero, who is destined
Powers and Abilities
Combat Empowerment - Inframan becomes stronger, faster, more durable, etc. when they come in contact with battle/fight, possibly unlocking abilities related to the affinity and enhancing the existing powers. Some users may be able draw sustenance from the fighting or even slow or stop aging.
Power Infusion - are able to fuse themselves with a power/creature inside object, beings or powers to combine their physical attributes with that of the creature or power. The complete acceptance and reliability of the contained power or creature are sometimes required to initiate the ability itself. The ending result being the user becoming many times more powerful and achieving enormous levels of energy. Users will gain markings on their bodies, and will also gain weapons to use.
Gamera (Heisei Trilogy)
Guardian kaiju. Able to spit plasma fireballs, high plasma fireballs, and ultimate plasma fireballs. Covered in a defensive shell and capable of quick regeneration (though perhaps not quick enough to matter in this setting). Unexpectedly, Gamera can fly: he has a jet-like High Mobility flight mode, where he looks like a sea turtle, and an offensive Rotating Disc flight mode, where he looks like a spinning chakram. Of course, he can also swim very quickly and is amphibious.
Haruko Haruhara
Alien space cop. Haruko rides a magical flying Vespa and wields an indestructible magical electric guitar. She's inhumanly quick and inhumanly strong.
Malenia, Blade of Miquella (Elden Ring)
The hardest boss in a game about fighting hard bosses. She recovers health with each attack she lands, even attacks that are blocked, and one of her signature moves, Waterfowl Dance, is basically undodgeable. Of course, depleting her health will trigger an even harder phase 2, where she retains Waterfowl Dance and opens with Scarlet Aeonia, an attack that hits almost the entire battlefield.
That's it for this bracket, since we're almost at the end of round 1!
Votes due by end of day Tuesday, September 26.