I believe this'll be a proper arc, spanning for at least several episodes.Granted, I do also get people's "frustrations" with a lack of "arcs" that being said, do remember, Mew is a series long (at the very least) goal, so Project episodes being spread out makes good sense too.
This series really has had some bad ones. Don't even get me started on the 2-in-1 episodes. Those are the most cringeworthy episodes I have ever seen.I hope that this will be the start point of a well written Arc, and I also agree that we've got tons of terrible fillers this season.
We don’t know that they’re filler but either way that seems pretty inconsequential in determining how many episodes are in the arc.The episodes in between are filler. And the title contains the phrase "Let's Go", heavily indicating that this is the beginning.