You don't see how Gekkouga spending approximately a year in the spotlight and having multiple episodes dedicated to its development and battles all in such a short time span was problematic? Especially since certain Pokemon like Onvern were practically overshadowed by Gekkouga's stardom? And please don't single out Pikachu as a counterargument: everyone knows that he receives a lot of screen-time, but that's never going to change no matter how much whataboutism is thrown his way.
No because it didn't evolve until before the 8th gym or in other word until after the 7th gym.
And did piss poor in the league only seen beating 3 Pokemon (Altaria/Sceptile/Bisharp; and only one was impressive) and losing to Charizard. Not to mention Greninja in its base form did terribly, struggling against Team Flare and only getting to do better when being in incomplete Ash-Greninja form).
It's focus was deserved otherwise people would complain Ash didn't struggle enough to get the Ash-Greninja form
Did Ash's other Pokemon get screwed over, yes, but that was going to happen regardless because that's all they are capable of or incapable of depending on how you want to look at it, but let's be more negative, they are incapable of balancing screen time between the Pokemon because they absolutely refuse to add more battles, more training or more bonding episodes to Pokemon who need it.
Look at 5th gen, all big battle competitions were a bunch of 1 vs 1s and the league was awful and we didn't even get a full battle that entire generation because DumbAF Nuts only brought 5 Pokemon. I'm not going to blame Greninja for the writers/producers for their poor decision making. Like not giving Noivern a really big battle to make up for not being used in the ice tyoe gym, as well as releasing Goodra.
And l ask this question, let's assume they allowed Ash to have Mega Charizard Y instead of Ash-Greninja why would Charizard's focus be less than what Greninja got. In fact Greninja would've been screwed over for Charizard and thus we're back where we started with Greninja being regarded as Ash's weakest fully evolved starter that should've gotten focus (Hence Torterra being excluded, since the focus was on Infernape not Torterra)
