Pokémon's Galar region contains four of the strangest creatures in the entire franchise, whose very existence is highly questionable, and the anime version of their Pokédex entries is the ultimate proof.

The fossil Pokémon of the Galar region are unique in that no complete fossils are available; instead, players are tasked with mismatching front halves of one fossil and back halves of another, creating bizarre hybrid creatures whose bodies don't function very well. Fans of the games were horrified when the concept first debuted, but the anime has done nothing to reassure fans in the episodes in which these creatures finally appear. In fact, Ash and Goh are the ones who actually create these Poké-abominations in the anime, and they don't even wind up with the creatures they expected to have.

Dracovish and Arctozolt's Pokédex Entries Were Made Up On the Spot

In the episode "A Pinch of This, a Pinch of That!", in which these fossils appear, Ash and Goh meet a researcher named Cara Liss who has a fossil reviving machine. The researchers have theories around the fossils, which they hope to prove by reviving them, however they intend to revive Arctovish and Dracozolt. The fossils get mixed up on the way to the machine, however, and instead revive Dracovish and Arctozolt, two completely different Pokémon created by combining fossils. This doesn't disturb Cara Liss or her companion at all, however, and they just make up new theories on the spot, which align with the Pokédex entries seen in the games.

Since Cara Liss is an NPC in the games who is also responsible for combining these fossils, it's fair to assume that she may be the one responsible for creating the Pokédex entries seen there as well. The fact that these fossil Pokémon have Pokédex entries seems to lend them some credibility, but their portrayal in the anime makes it clear that Dracovish and Arctozolt are chimeric creatures which never existed in the past, no matter what the Pokédex may claim. They weren't even particularly concerned with what to do with the Pokémon after the fact, as Cara Liss simply allows Ash and Goh to keep Dracovish and Arctozolt, respectively.

Getting to keep Dracovish certainly worked out in Ash's favor, as the one-of-a-kind Pokémon proved to be quite strong, and Dracovish played a crucial role in his victory at the Masters Eight tournament. Still, Dracovish's creation was a mistake that proves it never existed, and that the Pokédex information can't always be trusted, at least when it comes to these four fossils. The Pokédex is apparently just filled in by characters who discover new Pokémon, even if they have no way of knowing the truth of that Pokémon's biology and history.