Written by Jonathan Wojcik with the aid of With the Will, Digimon Wiki and Wikimon
I'm gonna say I don't quite like Gomamon X as much as Gomamon. It seems to just have shorter limbs, more red hair and drops the tiny, fang-like tusks. Its bio however mentions for whatever reason that it sometimes fights alongside Daipenmon, but considers the huge penguin to be its follower rather than the other way around, a cute idea.
ULTIMATE: PLESIOMON X
The rest of Gomamon's usual evolutions are skipped completely by X-evolution, but not its original Ultimate stage Plesiomon, which I still vastly prefer to the mammalian "Vikemon" given to him later. I'd say Plesiomon X is actually more interesting looking than the original Plesiomon, too, with a more shark-like face, a pair of whiplike whiskers and a skull swept back into a tapering crest; a more alien looking creature than your typical plesiosaur, for sure, and in a way that feels more befitting of an Ultimate level digimon. I feel like I should have always given Plesiomon at least a 4/5 to begin with, looking back on it now, so Plesiomon X is getting a full 5/5.