And thematically they all fit into the aesthetic of Japanese weapon techniques and military types. That would fit naturally in the timeline and setting of Legends.
Decidueye the archer, Smaurott the samurai and Typhlosion for canoneers and the Badger general/shogun yokai.
Now even more for why these were picked out of the rest:
Gen 1 starters just got their spotlight in SwSh
Gen 2 starters aren't as popular than Typholosion and Maganium was a focused Pokemon for New Pokemon Snap right off the bat.
Gen 3 starters got their spotlight in gen 6, Blaziken would conflict with Infernape's typing
Gen 5 Emboar's typing would conflict with Infernape's, Serperior isn't as popular as Rowlet, also its design is suppose to show European origins like the French (the gen 5 starter origin and main theme)
Gen 6 I guess they thought these guys just wouldn't work since they are more western influenced than eastern for the two and Greninja being a ninja instead of a honorable samurai might have made them pick Oshawott for more thematic reasonings.
Gen 7 Inciniroar and Primarina would not look right
Gen 8 They just showed up.
To have regional forms no matter how simplified it looks like from game mechanics, lore wise happen over many years after the pokemon living there have evolved to match or take advantage of the unique properties of said region.
Laventon literally just brought these starters over when he came. No time for adaptation, now will there be ancient Hissuian forms for the Sinnoh starters? That I'm more inclined to think might happen, even in the case of a form change.
- While I agree it's not too much of a stretch to equate Typhlosion with
daimyo due to its design, I find it unlikely that it has much in common with "cannoneers". Firearms and artillery were brought over by the Europeans in the sixteenth century--and even then, they weren't implemented in combat for a few decades. I think the volcano interpretation fits best in this case; volcanoes have many ties to legends, deities, and folklore, after all.
- To add:
Kanto starters: They have nothing to do with pre-modern Japan, and they have Mega evolutions and Gigantamax forms... like, really? (Don't forget Venosaur and Blastoise received the same treatment Gen VI meted out to Sceptile and Swampert in SwSh, though!)
Johto starters: Meganium is the cover 'mon of
New Pokemon Snap and Feraligatr is an alligator, which isn't even native to Japan. Typhlosion could be a myriad of things indigenous to Japan, but not so much that it warrants a new form. While the Cyndaquil line is the only "native" (or rather, continental--provided Unova and Alola are indeed based off the United States and Hawaii) starter in
Legends, Kansai and Hokkaido are radically different regions. The species would require time to adapt. (Even so, I'd say there's hardly a need due to Typhlosion's inherent nature. It would get along quite well in Hisui.)
Hoenn starters: Seeing as Hoenn is based off of Kyushu (located on the opposite end of Japan), which boasts its own near-extinct Ryukyu culture and unique fauna; I feel having any of those starters in Hisui would be counterintuitive.
Sinnoh starters: They've been shown to be native to the region, and I share the sentiment that it
might be possible for Torterra, Infernape, and Empoleon to have new forms. That being said, only Empoleon warrants it in proper due to the general application of the term "emperor" the world over. I don't see the need in the other two instances where Torterra is the token "tortoise landmass" mythos while Infernape is the product of the
Journey to the West saga, a tale that is popular across the Asian continent.
Unova starters: Serperior is not reminiscent of Japanese serpent legends. As for Emboar, I too believe it was overlooked because of repetitive typing, but it also has a very mainland(?) quality to it. Samurott was a given because it is the embodiment of something so distinctly Japanese. (And it is for that reason it requires no variant.)
Kalos starters: Gen VI presented us with the first cohesive group of third stage starters with human counterparts. Greninja had its time in the spotlight (plus, little-known fact, but ninja and samurai were not counterparts: the former did not come into existence until the sixteenth century or thereabouts), and Chestnaught and Delphox are deeply entrenched in European culture and have no place in the equivalent of pre-modern Hokkaido.
Alola starters: The decision to use Rowlet was a wise one, as archers have a place in Japanese legend and history; Hisui is a fine home for a Decidueye. Incineroar and Primarina are much too modern (and western) to figure into the cultural landscape of the setting.
Galar starters: This would be pointless, since you have them in SwSh. (Besides, imagine how ridiculous a drummer or soccer player or secret agent would be in pre-modern times!)
That being said, I can see GF re-imagining many starters they passed over from Generations IV through VIII with relative ease:
- A taiga or arctic Torterra (think of a fusion between Avalugg and Torterra)
- Infernape that more closely resemble native Japanese monkeys known for their fondness of hot springs
- Empoleon based on high-ranking members of the Japanese imperial court
- White Serperior reminiscent of those featured in Japanese lore
- Quadrupedal Emboar that run amok in the mountains
- A leaner, warring states period-style Chesnaught clad in plates that look like
yoroi
- Delphox as a full-on kitsune trickster
- Greninja could be vagrant warriors or thieves (not really sure about this)
-
Kabukimono Incineroar
-
Noh Primarina
-
Taiko drummer Rillaboom
- Performer Cinderace (there was a type of hackensack played in the courts, too)
- Scout Inteleon
I don't really need them to get new forms. Just new animations. I want to see Samurott actually pull a sword out and slice someone.
In
Pokemon Masters EX, I believe they have Hilbert's Samurott physically do that for its Sync Move animation, so it's probably not out of the question?