I don't know why Ash constantly dexes Pokemon he's already seen (within only a 50-60), the only thing I can think of is, the writers believe that debuting the Pokemon so early and having it be dexed then, means that people will have forgotten the information of it.
I might be able to defend Ash's actions better if the dex entries were different, but the way they portrayed Ash in this episode, it was almost as if he'd never seen a Scolipede before.
Or the writers are forced to constantly use the Pokedex, because it saves money, since the dex footage probably would be less expensive than the actual animation.
See I can understand Ash dexing something like his own Pignite, because the dex does show you a Pokemon's moves, he obviously did this with Swadloon and Boldore (though for the later he somehow knew the Pokemon in advance), but I highly doubt the dex would show the opponent's moves so unless the dex entries were different, I can't really defend Ash's dexing the same Pokemon over.
As for this episode it was better than some but others were better than it.
I really hope Krokorok's rivalry with Pikachu is resolved. Krokorok needs to interact with other Pokemon. Also I noticed Krokorok's size was fairly inconsistent, in some scenes Krokorok looked like he was taller than Ash being around 6' maybe less (depending on how big Ash is), and other scenes Krokorok looked smaller than Ash. I know Krokorok isn't supposed to be 6' but according to the ending his tallest Pokemon is between Spoiler:
Which is kind of sad.
I'll discuss the episode in detail, when I refresh my memory of what happened.