Okay, summer has been here for a while, but now I'm ready to get back to these reviews. These are going to be a little different than the ones before, in that Sinnoh is really out of continuity with what's going on currently in BW. So, rather than looking to see how well these episodes would predict the future and things like that (they don't, so no pt), I'll instead be looking more at how well the episodes are written and how fun they are.
I was totally blown away rewatching this episode. This is a really great one, really on par with the Rotom episode. I actually think there's much more thought in this episode compared to the Rotom episode; there aren't mindless (but funny) chase scenes here, but a real story, that someone with some imagination really developed out of something as trivial as pokemon stealing food. It's really incredible how one event leads to the other, and most of it really makes sense. The two things that are maybe overdone are TR's robot (although maybe that was the best said writers could think of to block the entrance to the underground water supply) and the way the group of Rattata and Nidoran get to the control room for the gate SO much faster than Swampert's swimming to Wailord. In fact, you wonder why exactly Ash jumped into the water in the first place. If he's really providing the protection necessary for Wailord, then the "dramatic" scene really isn't necessary. And it isn't, really. But those are honestly minor nitpicks. In fact, the fact that Ash jumped into the water was a very Ash-like thing to do, and I think it speaks to how comfortable Ash, Brock, and Dawn are with one another that no one is surprised at all that Ash does jump into the river like he does. There's plenty of scenes like that in this episode, and that's why it's as good as it is.
But, I know Cybercubed will read this some day in the next century, so I better defend this as best as I can. First of all, though Brock says very little in this episode, he's really important. The first scene is the one where Ash says he's hungry when the trio are discussing what to do now that the harbor is blocked by the Wailord. Dawn laughs, Piplup is unimpressed, Pikachu has a knowing, cynical smile, while Brock is exasperated. That's all that's really needed; no words are said, but the scene works. All of our characters are different, and I think that Brock's and Pikachu's expressions in particular have a "We know you too well, Ash" feel to them. Dawn is more good natured about it, but that's Dawn (Piplup is more expressive of its disapproval); she's also not traveled as long with Ash, compared to Brock and Pikachu. I also think this works both ways; if only Pikachu and Brock were there, I doubt Ash would be blushing as he is (less formality with Brock and Pikachu). But hey, despite his disapproval of Ash's "thinking," Brock still makes lunch. And you know, that's not meant as a knock at Ash at all. It's not that he can't think, it's just that he was being himself and showing that he's comfortable being honest in front of Brock and Dawn. Later on in this episode, we see him come up with a really brilliant plan to save Wailmer. Also, the decisiveness in having Pikachu act like an engineer when the gate needs to be opened for Wailord is all Ash's judgement. However, if Ash is the one willing to talk (and Dawn does as well) in this episode, then someone has to be willing to listen. That's what Brock does. Though he says very little, he does listen. You can also feel a difference in his comfort level when he's with Dawn and when he's with Ash. While Dawn is the one questioning Ash's decision to play engineer, Brock doesn't even blink; he's traveled with Ash long enough to know that's the way things go. He's also, again, really not shy to express his feeling of Ash's immaturity about saying that Ash wants lunch (in the same way Ash expresses his uncertainty about Brock's flirtations with girls). But with Dawn, Brock is a bit more hesitant and concerned. He's quite scared when Mamoswine launches Dawn up into the air, and it's up to Happiny to save the day. That may sound like a "Duh, Dawn's in the air!" statement, but I really think if that had been Ash, Brock would have been much more confident that Ash would have taken care of himself. Also, in the search underground, you can feel Brock is uncertain of what to do, and follows Dawn's lead in following Piplup more b/c he doesn't really have a plan himself. I really like the way it all worked out. I know next region, if this same type of episode had been shown (which it wouldn't have, b/c all old pokemon don't exist in the next region), then the 2 "other" characters would have been arguing the whole time during the search for Ash.
Sinnoh Ash really has a Goku/Naruto feel to him; the smile he flashes to Luxio (Oh goodness, I forgot its name) is one that's typical of that type of hero. Ash doesn't even blame the electric pokemon for being mad at him, instead just giving a sheepish smile and changing the subject.