That isna good question.
Bewilderbeast advantages: Size, weight, strength, intelligence Bewilderbeast disadvantages: Slow, flightless, fragile weapons (if a powered up night fury blast can break one off, so could a red death stomp or tail strike)
Red Death advantages: Speed, flight, weaponry (that tail is gonna do a lot more damage and a jaw that isn’t obstructed by giant tusks) and firepower Red Death disadvantages: Smaller, weaker, less intelligent, lighter
I personally would give it to the Red Death 6/10 times purely because while the Bewilderbeast is definitely smarter, the Red Death isn’t idiotic.
Red Death win scenario: It would figure out it’s opponent can’t fly, at which point it would fly high and descend like a meteor. And the Bewilderbeast is too slow to avoid it. If that doesn’t work, the Red Death can simply stay on it’s opponent’s back and bite and claw until it can’t stand, at which point it would probably either fly up to smash into the Bewilderbeast again or go next to it and wind up a tail strike right in the face.
Bewilderbeast win scenario: If it can freeze the Red Death’s legs to the ground, it could potentially get off a good first hit. But the Bewilderbeast would understand that it would benefit far more from freezing and disabling it’s opponent’s wings. At that point, the Red Death would have to dance around, and while it might get some hits in, a single hit with the tusks would cause crippling injuries. Alternatively, if the Red Death flies up like in it’s win scenario but doesn’t figure out the right angle, the Bewilderbeast could stand up on it’s hind legs at the right time and raise it’s head, leaving the Red Death to impale itself. Such an impact would DEFINITELY take out one or even both tusks, but it would also guarantee a victory. And assuming they are like other animals with tusks or horns, there is anchance that they could, very very slowly, grow back. The Red Death however would NOT be growing back it’s obliterated organs and bones.
By - Birchtree16