This is one of those episodes where the feelings you have watching it the first time, in the moment, are completely different from the feelings you have re-watching it, once the season is over.
I think, when I watched this the first time, I felt like this was one of Paul's finer outings. He was right, the majority of the time, and Ash was the one who showed a lack of knowledge. But I don't really feel that way now, and also, I think I notice now what a huge role Brock plays in this episode. It's your perception of Brock that really shapes this episode.
One of the sort of surprising trends in Sinnoh (and maybe forever...who knows?) is how little support Brock shows Ash. It's really felt more in Sinnoh; I don't think I really noticed in Kanto, Jhoto, Hoenn, or the BF. I think that since for Hoenn and BF, Brock had to share the supporting characterization with 2 other characters, anything he did probably wouldn't leave to big of an impression. In Kanto and Jhoto, Misty was the one traveling along, and she certainly didn't have any problems speaking her mind: Ash was being critiqued by both Misty and Brock (maybe not so much in Jhoto; more in Kanto, I guess). So Brock's actions never felt like that big of a deal to me. But Sinnoh is a different story, and that's all because of Dawn. Dawn supports Ash so much from a cheering perspective, and has a couple of times been ready to snap at Ash's other supporters in the stands for beginning to doubt Ash in the middle of the battle. There was a really funny scene like that where she gets mad at Brock in the middle of one of Ash's Sinnoh League battle, and Brock just smiles at her in response. For whatever reason, Brock just doesn't really cheer for Ash, and I really get the sense that, maybe from a strategy perspective, Brock maybe considers himself to be Ash's superior, and thus downplays the way Ash likes to battle. Or maybe he simply doesn't understand it, and that bothers him as a gym leader. I think there has to be something...and whatever it is, he doesn't get over it until Ash's final battle in the Sinnoh League, where he realizes something and starts to really cheer Ash on.
Brock's talk with Paul involves a good deal of manipulation, and whether that's for the good of Paul or for the good of Ash, is something you probably have to decide for yourself. Paul is surprisingly, or maybe not surprisingly considering he's talking to Brock, very open about his feelings here. This is interesting to note, b/c right before Paul battles Ash at the Sinnoh League, he and Dawn have a talk, and she has a much, much harder time getting a straight-forward story from Paul. But there's a difference in Paul's attitude in that scene compared with this one. When talking to Dawn, Paul is not as open about what he means, but I think he's more sincere. He's stating how he feels (something very, very difficult), and so it's no wonder that it's a little difficult to follow along. This type of honesty is also not laden with optimism; stating the way things w/o expecting a happy ending, or seeking a soln. Paul tells Dawn the way he feels in that scene, w/o any expectations of feeling better for saying what's he feeling. I think it's a way of accepting who you are, and I think a conversation is really fitting for Dawn, someone who, especially by that time in this story, has become her own person, and learned to appreciate life (she's not as focused on winning). Paul's conversation with Brock here is different; Paul is sort of complaining. And in doing so, he's expressing a sort of hope, I think. He still feels he's right. And a conversation like this is really fitting for a character like Brock, who I really think looks at the world that way. Brock is a sort of analyst: someone has to be right/better, and someone has to be wrong/need improvement: and more often than not, I feel, Ash is the one on the wrong/needing improvement side. I'm trying to think of a really serious episode where Brock has been forced to admit he was seriously wrong about something very important to him. And I can't really think of any; or feel any. Brock is the same guy as he was earlier, to me. So, this leads to the question: Is Brock right so much of the time? And the way you answer that question is the way you look at this episode, I think. Paul feels that way, that's for sure; he feels that way enough to really complain to Brock about the way Ash is training, and the way Reggie abandoned his journey as a trainer after failing to win the final frontier symbol. And you know, before I talk about Brock's response, I want to say a couple of things. I feel like Brock really believes he's giving the best advice; he has his own sort of confidence in that. It's a similar type of confidence to Lucian earlier when he advised Dawn on how to train his pokemon-and it's why I think Paul believes Brock is someone he can talk to (sometime in your life, you're probably going to meet someone like this). Second, it's really amazing how complex these characters are. I brought up Dawn a little on purpose, b/c when I was watching this episode, I was really thinking about a different episode, and that's dp 181. The ending scene of dp 181 is one of the most interesting, though a little disturbing, scenes that is in the Pokemon anime. I really, really believe that. It's an episode that's more famous for the shipping implications and stuff, but the final scene is more important for another reason, I think, on a friendship level b/w Ash, Dawn, and Brock. That scene (on a boat, as the trio is leaving for the Sinnoh League) is on 3 different levels, for each of the 3 characters, and why the characters did what they did is something that you really wonder about. It's when you realize these characters have a real life to them, and I think that was when it really hit me that Sinnoh was coming to an end. But after rewatching this episode, I think I'm not so surprised that Brock, at least, acts the way he does in that episode. And even Dawn now. I think you can really see the difference in those 2 characters in the different ways that Paul talks to Brock here and Dawn right before the Sinnoh League; it also makes sense for dp 181, I sort of think.
Brock holds back a really important piece of information when he talks to Paul about Reggie's travels, and that's that Ash did won the BF. That doesn't seem like such a big deal, but it really, really is. And so, Paul is really left under the impression that he's right. And so he makes a mistake. He doesn't really pay too much attention to what Ash is really doing in his training, as he's too caught up in talking to Brock (and we don't see what Ash does in the end, neither; all we hear is an explosion, and see Dawn's side of pokemon this time knocked down). Paul assumes that Ash is training just like he did earlier with Chimchar; throwing strong attacks at a pokemon, and have the pokemon focus its power to overcome and overpower the attack. He's convinced, and he even taunts Ash about it. But, unlike earlier with Paul's Wallace Cup accusations toward Ash, I really, really think he's wrong here. Ash is not trying to perfect a power move; he's working on a defensive move. What he has in mind correlates back to what we see at the very beginning of the episode in the battle b/w Aaron and Cynthia. I pointed out last episode that I thought Aaron lacked real creativity in the way he trained his pokemon; he focused on accuracy and power and hard work, and that's pretty much it. But I really felt like Cynthia probably understood battling on a whole other level, and she shows it in the battle in one scene: her Gastroden uses stone edge to block Beautifly's solarbeam(?), in a way that's very, very similar to the way Ash is trying to develop his new move for Fantina. That move didn't work for Cynthia b/c it flat out overpowered Beautifly's attack; it first was used as defensive move, and that's what created the opening for the attack in the end. Paul saw the same thing Ash did, but Ash is the one who really gets the jist of that particular move, and uses it to his advantage (he already had the idea for it before seeing Cynthia).
So Ash responds no way he's training like Paul; his pokemon trust him not to train them that way. He'll figure out a way to beat Fantina. Paul sees his chance (it's obvious at this pt he really just wants to rub things in to Ash-and again, I really get the feeling this is b/c of the talk he had with Brock just litte while beforehand), and, taking out his badge, says what's so tough about Fantina. Attack hard, and the ghost pokemon will not have a chance. Paul is trying to taunt Ash into seeing that power is what's most important, and, from Ash's perspective, his surest means of power is Chimchar's Blaze. Ash is now a good deal bothered (and he should be, b/c once again, he's defending his own beliefs-Paul has already won the badge, so even by winning the badge, Ash cannot prove Paul wrong-and the truth is, Ash is having to strain his thinking skills a great deal right now to make things work; I doubt Paul had to put this much thought into things, although probably there were a great deal of hardcore, simple training-like what Aaron does). Ash challenges Paul to a battle, which is 1-on-1, and right away Ash ends up at a disadvantage, type wise. But this is nice, too, in a way. As many times Ash and Paul have battled so far, I have yet to feel that Ash has really lost. The writers were really careful about things like this with Sinnoh Ash (next region Ash has had 2 really resounding defeats already to his main rival; the first battle had some tough circumstances, in a way, for Ash, but considering the pokemon he used for that battle, I can't say Ash really proved his worth as a trainer in that battle, or the next one he had). Ash does lose, and he gets a great deal of heat from Paul, annnnnnnnnnd Brock for the way he handles Turtwig/Grotle during the match. When watching this episode the first time, that's supposed to be the moral you take from this episode, that Ash was not experienced with using "tank" pokemon. It's a really interesting dynamic, that's for sure, the way it's set up here. Of course, having trained his own Turtwig all the way to a Torterra, Paul would know all about the loss of speed. And this sets up something really important, as well, in the way you look at this episode, and that's Torterra's motivation for helping Grotle (by the way, Grotle's frustration at night when it trains alone is a really beautiful, emotional scene). Paul taunts Ash for not recognizing what has changed, and even Brock catches on right away and gets on to Ash (technically Brock's criticism comes before Turtwig evolves, when he tells Ash that he's dodging too much and not very good at timing attacks when there's an opening-but you know, I think that's the whole pt of why Ash is developing a new move for defense, b/c he has trouble with that specific timing-but that's also odd in a way, b/c he's had to work with Aipom's focus punch before, and he was proficient at timing that-, and maybe that explains why Ash's use of Grotle for the remainder of Sinnoh is the way it is-there feels like there should be more to this story, even though Sinnoh is now over-, but I think that was just hinting at Ash's problems with Grotle after the evolution; Brock would have gotten on to him anyway); but Torterra has real sympathy. And, I think, generally, you have real sympathy for someone else's troubles when you've been though something like that yourself. It's why, I think, Ash got along with Dawn, when she has her confidence troubles, much better than Brock or Zoey did; he's really had some tough times on his journey, especially towards the end of the BF and beginning of Sinnoh. For Torterra to go out of its way to help Grotle as much as it does, I think it had to undergo a similar type of learning curve. It was in that position once; it was that frustrated (although it probably didn't have quite the huge speed that Ash's Turtwig did). And so, it decides to help out. Judging from the way Paul acts, you wouldn't think that (and Brock sort of reinforces this in the way he acts); Paul seemingly had this all figured out from the beginning. But I wonder if he really did, and I wonder if part of the reason Torterra shows its act of defiance (which it is, in a way) to Paul is b/c it's trying to remind Paul a little that he had some troubles too. It's fun to think about, and there's no real way to know.
This felt like a really long review, and most of this was just conjecture. One more thing, which is a bit more concrete and less opinionated, is again how well this group of pokemon work together. They interact really well, and this starts from the writers thinking of ways to have most of the group out together pretty frequently. Even though this episode is about Grotle, for the most part, Gliscor, Piplup, Chimchar, and Staravia have really strong appearances. You really note that they show up in the episode, and that's a real positive.
So, I suppose what I meant to say at the beginning of this episode about the way you view Brock being a big influence on how you look at this episode, is that either you see Ash as looking like an inept trainer (one with limited experience, but a great attitude) or you see how Brock instills a sort of "false" (if you see the first episode of the Sinnoh League battle b/w Ash and Paul, you'll sort of see why I call it "false," with reference to a specific move Paul uses that catches Ash by surprise) confidence in Paul that he's right, with a little misfortune in the timing of Turtwig's evolution providing further proof to Paul that he's the better trainer (and maybe Brock, too).
Edit: It's not dp 181, but dp 180.