Gen 5’s stupid evolution levels don’t even make sense in the context of BW1. You would think it would have a high-level endgame (like XY, DP, or SwSh) but it’s on the lower end with levels ending around 54. Completely bizarre
It definitely did not make sense for where you caught them. People keep saying this but it really doesnt work out.
I took a Vullaby through the entire game and it did not evolve until the post game.
Level 54 is a very high level, the highest level you face is Ghetsis' level 54 Cofagrigus. You are much more likely to finis hthe game with pokemon in their high 40s to very early 50s then you are to naturally hit Braviary/Vullaby's evolution levels. Even Bisharp (level 52!) is probably at best going to be a Bisharp for like...Ghetsis. Maybe N.
Okay, this post in particular is kinda old, but I wanted to address this. Namely, after really thinking about it, I think I have a pretty decent idea of what they were thinking when they designed several of Gen 5's later Pokemon and their obscenely high evolutionary levels.
Basically, R_N pointed out that it's unlikely anyone will be able to evolve several Pokemon such as Mandibuzz, Bisharp, and Braviary until roughly the post game, and that you are likely to "finish" the game with your team at high 40s-50s. But that's the thing, you "finish",
quotation marks emphasized, the game at that point against N and Ghetsis.
This is what I'm thinking: BW1 is very likely designed with a mentality similar to the Johto games, in that it's designed with the mentality of
"You are not done until you have finished the post game".
The key thing to remember with BW1 is that it has a very notably massive post-game segment after the first visit at the League+Team Plasma. BW1 has an entire half of Unova left unexplored for the post-game, plus several notable post-game locations such as the Dreamyard, Challenger's Cave, and the Royal Unova, as well as higher level Elite Four rematch at Level 70+, which also has a proper battle with Alder at Level 75, with his ace (Volcarona) at Level 77. Cynthia is also a bonus boss with her team at the same levels as Alder.
The game
wants you to keep going after Ghetsis. After the first E4 battles and the showdown with N and Ghetsis, the game is basically like "No, it's not over yet". The game immediately gives you a quest involving Looker, which involves hunting down the remaining Six Sages for Looker to take into custody. And of course, an entire half of the region is still unexplored. The game's story is really,
really not over after defeating Ghetsis, because it wants you to do this and have Looker capture the rest of the Sages to end off Team Plasma, and in doing so you're expected to continue exploring the rest of Unova, especially the eastern half of the region (Routes 11-15), possibly capture Landorus and Kyurem (who are both post-game legendaries), and then after your team has gained substantial experience from all those battles you have along the way, have one final showdown against the Elite Four, and end off your Unova adventure with one final, proper showdown against Alder, who is the Champion you didn't get to fight beforehand, followed by a real and formal Hall of Fame indictment and a second credits sequence.
See where I'm going with this? Everything before N and Ghetsis, including the Gym Challenge, is essentially the "first half" of the game, while the post-game segment afterwards is essentially treated as the "second half" of the game (even if it's more non-linear and free-form). This is the point of the game where Pokemon such as Mienshao, Braviary, Mandibuzz, and Bisharp are designed to shine: the idea with the later Pokemon of the dex is that you obtain them, raise them for the later segment of Part 1, then once you're in post-game, or in other words, Part 2, enjoy their fully evolved forms while grinding your way through the rest of the battles you have in Eastern Unova (all of which are Level 60+) until you eventually use them in the second League challenge where you face the Elite Four at their full power as well as actually battle Alder. At the point you face Alder, which is Level 75+, you should already have a Hydreigon as well (if you choose to catch and raise Deino, you will spend much of the post-game struggling with the Zweilous phase like I did in one of my most recent playthroughs). There are many, many battles to be had in the post-game half of Unova, which gives you a lot of time to finally enjoy these Pokemon and use them to their full potential in the post-game as a reward for sticking with them. Granted, this is less the case with Hydreigon, but again: Deino is designed to be a post-game pseudo-legendary that is meant to be raised and struggled with in the latter half of the region.
Essentially, the "true finale" of BW1 is not actually Ghetsis, but rather Alder. As I said, the game expects you to take your team from the whole Team Plasma castle segment and carry it over to explore the eastern half of Unova and several other post-game areas, and then battle the Pokemon League again once you're ready level-wise. In that sense, BW1's
true endgame levels are around Level 75-77 with Alder's Volcarona being Level 77. Once you "really" complete the game's adventure for real, your team should ideally be somewhere in the 70's. That's around 20+ levels you get to enjoy stuff like Bisharp, Mandibuzz, and Braviary in their fully evolved forms. In the case of Deino, you should already have a Hydreigon by this point after putting in so much effort throughout the post-game to get it to the final stage.
This is the case with BW in particular because the Gen 5 Pokemon's levels are designed with a curve relative to the point of the game you obtain them in BW1: for example, three-stage evolutionary lines like Sandile, Gothita, Solosis, Vanillite, etc. are designed in such a way that you spend at minimum around 10-11 levels in Stage 1, and another 10 or so in the second stage, and vice versa. Every evolutionary line has their levels set in such a way that you spend at least 10 levels with each evolutionary stage: this applies just as much to the later Pokemon in the dex, where they evolve around 10-15 levels from the point you obtain them. But in these cases, they are expected to be trained from the 7th Gym-8th Gym onwards and into the post-game, where the whole post-game segment gives them the opportunity to shine, and again, to put my whole point bluntly:
the post-game is still considered part of the main adventure of the game!
BW1's adventure is very unconventional in that the main story does
not end off with the first challenge against the Pokemon League: no, it's designed to end after the
second match against the Elite Four, which is where you really fight the Champion, who in every Pokemon game is designed to be a Pokemon's game final boss: and in this case, despite what it may seem, Alder is
still the formal final boss of BW1 and the match against him is, for all intents and purposes, designed to be the true endgame of BW1.
TL;DR Unova, namely BW1 is very likely designed with a GSC-esque mentality of "You aren't done with the game until you've completed the post-game". Even after Ghetsis, it wants you to continue exploring the rest of Unova, namely the eastern half, with some more story tidbits involving Team Plasma, and expects you to keep training your team until you are ready to rematch the Elite Four and actually battle Alder, which puts some of the Pokemon's stupidly high evolutionary levels into perspective: the late-game Gen 5 Pokemon, such as Mandibuzz/Braviary and Bisharp, are designed so that they are meant to shine in the very extensive post-game segment of BW1, which gives them an opportunity to have substantial time to be used and enjoyed for a certain half of the adventure (which isn't something a lot of late-game Pokemon get to have). The post-game is, for all intents and purposes, still part of the main adventure and is more akin to the "second half" of the game, albeit more free-form than the first half.