Why can Pokémon appear at higher levels in Y?

Question

I was looking through the location guide on this website, and it says that some Pokémon will appear in both versions, but at a higher level in Y? For the example, on route 21 in X, Dragonair only appears at level 50. But in Y, it appears at levels 50-55.

Comments

https://bulbapedia.bulbagarden.net/wiki/Kalos_Route_21#Pok.C3.A9mon According to Bulbapedia it's the same for both games.

---

Bulbapedia is wrong.
https://www.serebii.net/pokearth/kalos/route21.shtml

Answer 1

I tested this out and it seems that this actually isn't the case. On top of this Bulbapedia page stating otherwise, I tested it myself in Y. I used a level 57 Skarmory with Keen Eye at the front of my party, (assuming that Keen Eye's outside of battle effect works while fishing, this should have made it so I would have encountered Pokemon 52-57 half of the time) and fished with the Super Rod. All of the Pokemon I encountered were level 50.

UPDATE:
As sumwun suggested I do below, I put a Hustle Zweilous (in case it's important, it was KOed and on level 59) at the front of my party. All Pokemon that were fished up were level 50.

Comments

Have you tried using it with pressure, hustle, or vital spirit? Because keen eye works by preventing low-level encounters, and something that prevents encounters in tall grass might not work in fishing. Pressure, hustle, and vital spirit work by forcing Pokemon to appear at the highest possible level, and I know for sure that they work in fishing.

---

No, I haven't. I will now.

---

Thanks for the help. I would’ve tested this myself but I don’t have Y.

Answer 2

I honestly don't know but my prediction is that Game Freak is encouraging players to buy both versions. this applies to oras, sun, moon, ultra-sun and ultra-moon.