literally the textbook definition of a tsundere
Can't really agree with this, Mega Evolution drives the A plot of XY, the B Team Flare plot only begins after the almost conclusion of the Mega Evolution storyline.-Just better incorporation into the plot in general. Even in XY Mega Evolution only really had a tangential relationship to the Xerneas/Yveltal stuff. Meanwhile in SWSH, Dynamaxing is totally baked in to stuff like Legendary role and the spectacle-based sports culture of the Galar region.
To elaborate on A and B plots, every game since Gen 3 has had a pretty clear split between two storylines, the lesser stakes initial plot that generally covers why the player leaves town to start with, and the "main" plot that generally ties to the legendary. GSC kinda sorta has this with Team Rocket starting at the lake of rage, but this wraps up pretty quickly and I'm not sure it fits.
For RSE - the A plot is the player going to show off their new Pokemon to their dad, being recommended that they go collect badges so they can fight Norman, and it wraps up right around after Norman's beaten. The B plot is Magqua, and that only really starts to kick off with Mt. Chimney, but more properly after Mt. Pyre, and this drives the player through to Sootopolis.
For DPP - A plot is arguably about chasing Barry and following him through the gym challenge, it wraps up extremely quickly and the B plot of Team Galactic strikes early and hard, beginning basically right after getting the first badge and then never letting up.
For BW - the A plot here is about going out with Cheren and Bianca to figure out what you all want to do, and this reaches a concluding point right around Nimbasa, with Bianca wrapping up her conflict in the city and Cheren getting hit by Alder right after the 4th badge. They have a bit more development after this point, but the B plot absolutely kicks off here, with Team Plasma starting to take a more central role in driving the game forward and N revealing himself as their leader by issuing a direct challenge to the player.
BW2 - the A plot is probably Hugh's journey? The A plot here is pretty weak no matter how you look at it, and the B plot of the Plasma Pirates comes in suddenly and somewhat abruptly, though it does a decent enough job carrying the game unlike the GSC Rocket plot which is more of a diversion than anything.
XY - the A plot is Mega Evolution, this drives basically every location the player goes to once they've met the professor and reaches a conclusion when the player beats up their rival using a Mega Evolution (which totally happens canonically trust me) outside the 4th gym. The B plot of Team Flare developing into an active threat happens right after this, so I think it fits.
SM and USM even though USM's changes are garbage - the A plot is going through the island challenge because the player is new and why not do it (it's not a strong A plot). The B plot is, in SM, much stronger and kicks off with Lillie's kidnapping, as the player goes out to help fix the broken family (SM) or go take over from the definitely well meaning extremist when she fails and endangers the world (USM).
SwSh I haven't played so if I'm missing some detail I apologize. The A plot seems to be "player goes off to become champion", I can't fit in the character development of Galarian Hau here because from what I've seen it never actually drives the players actions, it just kind of happens around them as they continue to battle. The B plot happens right before the champion and wraps up there too and I'm not a fan but it's clearly its own plot, it drives your actions and is not connected to the "break the unbreakable, beat the unbeatable" thing most of the game has. Dynamax um. Relates to this very abrupt B plot.
Well that was a tangent I guess. Kanto really doesn't have a split between an A and B plot, the entire time the game is pushing the player to catch up to and beat their rival (this is actually really clear when you consider that there's just a random rival battle in the middle of the team rocket climax) while everything like Team Rocket is just there In The Way between the player and the next gym.