The Pokemon series is no stranger to outlandish fan theories, such as Chairman Rose rigging the Galar League to allow Leon to go undefeated for so long. One of the longest-running theories in the series began all the way back with the original Pokemon Red & Blue and revolves around Cubone and the mystery of who its mother is.
While this theory has yet to be confirmed or denied by The Pokemon Company, they have gone out of their way to reference this theory multiple times in the series so far, particularly in the more recent generations of video games that introduced S.O.S. battles and in the Isle of Armor DLC.
5 What Is The Kangaskhan Theory?
Although this fan theory revolves around the identity of Cubone's mother, it's often referred to as the Kangaskhan Theory, as this is who many fans feel is Cubone's mother.
In the original games, many Pokemon went through changes when it came to their evolutionary lines, such as Venomoth and Butterfree seemingly being switched and the original Blastoise looking very different from its final design. This is a side of the series that has persisted throughout the generations, with some fans believing that Kangaskhan was supposed to be the final evolution of Cubone, with Marowak being the middle evolution, though was later scrapped in order to be a stand-alone Pokemon.
4 How Fans Reached This Conclusion
The theory began when players noticed a striking similarity in the design of Cubone and the baby that Kangaskhan carries around in its pouch, as their bodies are essentially identical with the former wearing a skull on its head. In later generations, the fact that Kangaskhan was also made to only be female added to the idea that it was Cubone's dead mother, as there is never any mention of Cubone's father in either the anime or its Pokedex entries.
Over the years and generations, while the true identity of Cubone's mother is still heavily debated with no formal take from Game Freak or the Pokemon Company, there have been several clues added into the series that have added weight to the credibility of this theory.
3 Evidence In Favor Of The Theory
The biggest clue that Cubone and Kangaskhan are connected on a deeper level comes from their respective designs. While there are some differences, the most obvious being that Cubone is a Ground-type while Kangaskhan is a Normal-type, it's hard to ignore how similar the pair look in terms of their body shape. Both Cubone and Marowak have the same light coloration on their stomach as Kangaskhan and her baby as well as a tell-tale tail spike that appears in all three Pokemon.
In generation seven with the introduction of S.O.S. battles, more evidence was given to players that suggests a connection between Cubone and Kangaskhan, as a wild Cubone would, on rare occasions, call a Kangaskhan to fight by its side.
In the Isle of Armor expansion for Pokemon Sword & Shield, several old Pokemon returned to the game, including both Cubone and Kangaskhan, with both Pokemon being found in the same cave area of the Isle of Armor.
2 Evidence Against The Theory
While there is a large amount of evidence in favor of this theory being accurate, there are also some aspects that can't be ignored. The difference in typing can be brushed aside as simply being due to the fact that the supposed baby Kangaskhan is wearing its mother's skull, resulting in its type change, but this isn't something that happens in the world of Pokemon and only really happens with regional variants.
The biggest piece of evidence against Cubone being the baby Kangaskhan, however, is in the same boat as the biggest piece of evidence in favor of this theory: its body. While there are some similarities between the two species, its hard to ignore the fact that the skull that Cubone wears is far too small for it to have come from a Kangaskhan, and this isn't even taking into account the fact that the shape of the skull is also not a match for Kangaskhan. Most notably, the horns on Cubone's skull don't appear on Kangaskhan at all and are the main cause of debate between supporters and detractors of this theory.
1 Alternative Theories
Kangaskhan isn't the only contender for the identity of Cubone's mother, as some Pokemon fans have pointed out that there are other candidates that are equally as likely. Aside from the mother Marowak, which seems to be the most obvious choice, some fans believe that Cubone is actually a baby Charmander whose tail flame has been extinguished following the death of its mother Charizard.
This theory comes from not only Cubone and Charmander having similar body types, but the fact that the skull that Cubone wears is eerily similar to Charizard's head, complete with the horns that Kangaskhan doesn't possess. This theory would also explain how Alolan Marowak gains the Fire-type in Sun & Moon and how Kantonian Marowak can learn Fire-type moves like Flamethrower and Fire Blast.