While this is a retread of FWF, there are a couple of key differences to this episode, making it unique enough and not simply a carbon copy of FWF. Considering these, i think, reframes the episode somewhat, and is important to be able to break away from comparing it to FWF and enjoying it on it's own
1. This episode portrays how AJ and RD tryinig to one up each other can put others at risk, whereas FWF completely skipped over this. Any of the traps set by RD and AJ in the latter could've easily gotten someone hurt, yet that idea wasn't explored. Here on the other hand, such dangers are the primary focus of the episode.
2. The idea of this is somewhat different too. How i see it, FWF was mostly about keeping competition friendly. On the other hand NCC seems to explore the idea of cases, where competition is detrimental to the core activity. In this case the school activity is supposed to be based around and promote cooperation.
3. Some say that the episode is pointless because AJ and RD didn't learn anything. I think that it is simply natural for their characters (in terms of psychology) to interact in that way, simply put their competitive natures will always clash in some way and that is completely fine. Their arguing at the end doesn't necessarily conflict with the main idea of the episode either as described above. On top of that, while it's impossible to really confirm if the idea of the episode stuck with AJ's and RD's characters, this was as much of an episode for student six as well. Not that they are the only ones that learned anything, but it is something to take into account too.
The point about them "almost letting someone drown" is also somewhat misused i think. While it is true they probably should've made sure everyone was okay first, they took the necessary precautions beforehand(life vests) and what happened to yona's vest was very coincidental. However when they noticed something was wrong they didn't go on arguing and had started analyzing the situation and working toward the solution, they simply weren't quick enough to compete(ha, get it) with an actual fish and a shapeshifter. More importantly, it gave the episode a huge sense of stakes. Of course, not every episode in a show like this needs to threaten someone dying to create tension, however used sparringly it can become, i think, a strong x factor for an episode. If you actually expect someone to die in MLP of course.
The execution of the episode could've been done better, some of the humour didn't hit that well and the learn from the opposite idea could've probably been done a little better. It wasn't an exceptionally good episode, however i think it definitely wasn't as bad as many make it out to be. Perhaps the community just became much more keen on picking apart episodes it considers subpar due to how much people want to see the show do as well as it did in their favourite episodes. And, of course, constantly comparing it to FWF doesn't help either even aside from being used as an example for the previous point.