Cinderrace is still his partner Pokémon and pretty much the Pikachu of his team, the OP pretty much shows Cinderrace alongside Pikachu at the beginning the first poster has Cinderrace alongside Ash’s Pikachu. The anime doesn’t need to say that they are starter Pokémon because they know that the viewers know that they are starters. Again every character that has appeared in the anime who’s main partner is a starter Pokémon did not return to series as a main cast member again. Otherwise May, Dawn, Serena, and Lana could have pulled a Brock and returned as part of the main cast again.
Yeah I understand your concern about Sprigatito, which is why I am hoping that it stays on all four legs instead of two.
Brock's Onix is iconic even back then. When people are asked of who is Brock's Pokémon, it's always Onix. Big boulder snake is very easy to remember and Brock often used him during the many battles against Team Rocket. Yet Onix got benched by the time of Gen III. And Brock's Forretress is not available to catch in Ruby and Sapphire (that wouldn't till Emerald), so Brock went into Hoenn with a non-marketable Pokémon even though he has Geodude.
Cinderrace is used as a counterpart to Lucario, not to Pikachu. In the OP, it's Grookey and Pikachu.
Really, I recall that this argument didn't really existed until Goh showed up and I suspect this is another moving the goal posts.
Prior to Goh, the biggest argument against May, Dawn, Iris, Serena and Lana joining Ash in the next series is the fact they are all based on game characters with specific goals to promote the current generation, and thus will retire from Ash's group once that generation ends and a new one begins.
But Goh has no game counterpart. He's an original character in the anime, and his goal is so nebulous that he could literally go to any region he likes and it will still fit with the series. Gotta Catch 'Em All. Oh sure, he wants to catch Mew. But that's like saying Ash will retire after he beats Leon. Like no, Goh will not simply retire if he caught Mew. His ultimate goal is catching all the Pokémon, it's just that Mew is the first physical step to realize that goal just like Ash defeating Leon is a physical step to becoming Pokémon Master.
If one were to expect Goh to leave the series just because his universal goal isn't enough to go to the next region, then I will say it is also just as likely we see Ash leave the series because his goal may not align with SV's new regional gameplay. Ash and Goh can adapt and to say one couldn't is simply making the case for the other to leave as well.
