This is pure opinion, and while it may be a popular one, it's purely and simply just that, an opinion. Quite frankly it gets old seeing posts about how the pacing of a Pokemon's, or a character's development should be so different.
It's actually half opinion half fact.
The opinion half comes from personal preference.
However the fact half comes from that a lot of Pokemon get development a lot earlier, than Noibat has. Like Goomy. Goodra was on the team for a lot less and has more development than Noibat.
So no it should've happened sooner, the writers/producers just didn't give a crap therefore only making it opinion of personal preference that it should've happened sooner.
It is also a fact that some Pokemon get screwed over in comparison to others.
What I find interesting is however, there was no reason for it. Literally the only excuse the writers/producers could ever use that would even be remotely legitimate is that Yuka Terasaki had scheduling/personal conflicts and couldn't voice Noibat, which the only ever excusable explanation.
I'm somehow supposed to otherwise believe if that wasn't the case, that this supposed marketable Pokemon has NOT been showcased until technically the Terminus episode.
I'm also to believe that somehow Noibat being an egg Pokemon and it receives NO development until the number of episodes, where technically any other type Pokemon would likely be evolving?
Noibat is the worst egg Pokemon to ever appear in the anime belonging to a character that actually has a goal. Most egg Pokemon have already received focus by now.
And let's not forget Eevee. Eevee has had plenty of development enough that it is ready to evolve, and likely before Noibat does, and Eevee was captured after Noibat. For all we know Eevee could be younger than Noibat for all we know, not that MUCH younger but still younger.
I was fine with Fletchinder evolving, and of course Frogadier evolving, but NOT one episode dedicated to training Noibat, NOT one single scene of it using a damaging attack against an opponent until 20 episodes after its debut.
There is no just excuse, the horrible treatment of Noibat really makes me hate that Ash even got a Goodra, because that obviously a waste of 7 episodes on a Pokemon we're are likely to never see again. 7 episodes out of 17 were devoted to the Goomy line.
And since Olympia, Frogadier/Greninja has gotten at least 4-5 episodes of massive focus and STILL has more to come.
And let's also not forget Hawlucha, Hawlucha is an even worse shape than Noibat, since it last got focus in the Sky Relay episode but Noibat is getting 2 episodes on Hawlucha unless it appears in the Bonnie episode or this particular episode.
Talonflame's appearance is starting to wane since Olympia.
At this point, there's just no excuse for the jarring absent appearances of the Pokemon, at best we can only hope for XY&Z Episode 1 where they all appeared for a cameo appearance.
But again let me perfectly clear. I am fine with this episode, better this than nothing. Just don't expect me to all that grateful about it when its happening 27 episodes after the Sky Relay episode, and not sure how much of Noibat's appearance in the Terminus Cave eased up the long gap.
Remember Palpitoad? No, well you see what I mean?
And that was excused because Ash had so many Pokemon, HE DOESN'T have that many Pokemon, so there's really no excuse.
But whatever people will believe whatever they want in regards to the series.
Just let me have my beliefs.