Dipplin and Hydrapple were both introduced as new evolutions of the Applin line in the Pok\u00e9mon Scarlet<\/em> and Violet<\/em> DLC, and Kieran might\u2019ve been the one to discover that final evolution according to one fan theory.<\/p>
Kieran\u2019s character arc and Applin\u2019s new evolutions were two big aspects of The Teal Mask<\/em> and The Indigo Disk<\/em> DLCs. Through the two-part story, we watched as Kieran went from being the shy kid to becoming the arrogant BB League Champion, motivated to be better than the player. During this period of growth for Kieran, his Dipplin also evolved into Hydrapple at some point after The Teal Mask<\/em> and before The Indigo Disk<\/em>. According to an interesting headcanon in a Jan. 15 Reddit thread<\/a>, this could\u2019ve been when Hydrapple was first discovered.<\/p>
The headcanon talks about the specific circumstances involved in the evolution process for Dipplin and Hydrapple, and they do align with Kieran\u2019s background and story. Currently, Applin\u2019s evolution into Dipplin is tied to Kieran\u2019s homeland, Kitakami. The apple stand in Kitakami\u2019s Mossfell Confluence is the only place to obtain the Syrupy Apple<\/a>, the item required to evolve Applin into Dipplin<\/a>. <\/p>
At this point, Hydrapple wasn\u2019t in the Gen IX games yet, though an evolution was unofficially confirmed due to Dipplin\u2019s interaction with the Eviolite<\/a>. Perhaps Hydrapple wasn\u2019t even discovered yet by people in the Pok\u00e9mon<\/em> world. Otherwise, Kieran would\u2019ve been the type to evolve his Dipplin as soon as possible in an attempt to outshine the player.<\/p>
We see Kieran finally has Hydrapple by the time The Indigo Disk<\/em> starts. To evolve Dipplin into Hydrapple<\/a>, you need to use TM226 on it to teach it Dragon Cheer, and that TM is currently only distributed by Drayton at Unova\u2019s Blueberry Academy\u2014Kieran\u2019s school. So Kieran essentially brought his Dipplin (which requires a Kitakami-exclusive item) with him to Blueberry Academy (the only place to obtain TM226 Dragon Cheer). In other words, Kieran checked off the two location-specific requirements to get his Applin evolved up to Hydrapple.\u00a0<\/p>