Huh? It’s evolving!
Looking at the images of these two Pokémon, there is a similar structure shared between them. But the real evidence comes from Pokedex enteries.
“It is thought to have inhabited beaches 300 million years ago. It is protected by a stiff shell.”
-Kabuto Dex Entry Pokémon Diamond/Pearl/Platinum
“Over 300 million years ago, it was feared as the strongest of hunters. It has been modified by Team Plasma.”
-Genesect Dex Entry Pokémon Black
It’s safe to say that if Kabuto is around, then Kabutops would be around, too. Kabutops is also described as a hunter. From the Dex entries, it is believed that Kabutops’ evolution to being on land was solely due to following their prey. This results in Kabutops being the Pokémon that was modified to become Genesect.
It’s only one Pokéemon
This theory is focused on Gengar. Gengar is really the only Pokémon in its evolutionary line. Gastly and Haunter are stages and forms of the ghost/poison Gengar entering the physical realm. Large piece of evidence comes from Gastly and Haunter having the same weight. Both are listed to have a weight of 0.2lbs. I want to take note that Haunter is a full foot taller than Gastly. When finally evolving, or rather emerging, as Gengar, he is 89.3lbs. A sign that the Ghost finally has a physical form. So congrats on evolving that Haunter! You’ve just brought a Ghost into the world!
Evolution of Time
Aerodactyl evolved into Zubat, but not in the same way we usually see Pokémon evolve. Rather, over the course of millions of years, the Aerodactyl did not so much go extinct, but rather transformed into Zubat. Some evidence comes from their shapes and structure between them and Zubat’s evolution. Aerodactyl’s shiny version have a similar color scheme to Crobat. Also they have common attacks; Bite, Supersonic, and Wing Attack. Just imagine walking through caves and encountering an Aerodactyl every 5 steps.
This theory bases around the appearance of Venomonth and Butterfree to their previous forms. And by looks alone, it seems these two may have been switched. Venonat shares more common colors with Butterfree and similar eyes. Venomonth shares more common points with Caterpie and Metapod as well. Was this intentional, or did an accidental switch become a permanent place in Pokémon history?
The Failed Mews
A.K.A. Ditto. Mewtwo was the only one considered a successful clone of Mew. But what about all those the attempts before Mewtwo? Those failed results became Ditto. There is multiple pieces of evidence to support this. First, Cinnabar Island where Mewtwo is encountered is also filled with Ditto. They share: color, weight, and gender. The only two Pokémon that can learn the move Transform. Even the supposed successful copy can’t learn that move.