From a "lore" standpoint... Maybe. They're definitely not Johto-native.
However I'd argue that Slugma is more likely native to Hoenn than Kanto. My personal understanding/headcanon is Slugma only started appearing in Kanto because Cinnibar erupted, spitting them everywhere.
>>37959336Nope, not at all. Voltorb was originally found at the Pokéball factory in Kalos, for one. Exeggutor has been widely implied to be originally from Alola.
Mr. Mime are also only very rarely found in Kanto and other regions, yet are a common encounter along with entire hordes of Mime Jr in Reflection Cave in Kalos. Due to the namesake and theme of the cave, the fact that it's the only place these "rare" Pokemon are found commonly, and the obvious France/Mime theme, it seems like a no-brainer to me that Mr. Mime originated from Kalos.
Prior to LGPE, I would have also pointed out the Safari-exclusive Pokemon like Scyther can't be native to Kanto, but well... They clearly are, or at least have rare migrations there. Scyther is still most likely from Sinnoh though, in the tall grass location at the bottom of Mt. Coronet.
Oh, and Ponyta - Ponyta and Rapidash only appear at the man-made bridge route, and not in the "wilds" of Kanto, and as such I believe they're actually native to Sinnoh. In Sinnoh they appear right by the Ranch, although that of course could indicate the Ponyta were brought to Sinnoh.
Speaking of ranchmon though, there's Tauros (and his counterpart Miltank) - Alola is the only region where these Pokémon can be found in the wild away from any civilization or ranch/farmland, at the Poni Island plains. The Dex says the Alolan people were the first in the history of the world to tame them to ride and use, so being a rare spawn and original Safarimon, Tauros most definitely is native to Alola, not Kanto.
