Pokemon games have a long history, with plenty of them innovating upon older releases while still featuring some recurring features and themes of the series. One of them is that players are usually able to pick their first Pokemon from a set of three new monsters, and while some entries in the franchise have taken a different approach to this, starters are always a huge part of the experience. Another example is that mainline Pokemon games often have multiple Legendary Pokemon available in the game, with a number of those critters being version-exclusives.
Legendary Pokemon have a huge appeal because of the power fantasy they embody, as they are often mythical creatures with immense powers that also have in-game effects through unique abilities and exclusive moves. For many players, choosing the game version they'll be playing revolves around the Legendary monsters on the cover, as they are guaranteed encounters in that specific game. However, the fact that every mainline Pokemon game allows players to catch multiple Legendaries is not necessarily a good thing. It may take that uniqueness away, and sometimes it doesn't really make a lot of sense in terms of the universe's lore.
Why Catching Legendary Pokemon is Not Always Right
Legendary Pokemon are powerful, ancient creatures from the myths of a given region, and they often control the elements - such as the weather trio of Pokemon Ruby, Sapphire, and Emerald. They may also be deeply connected to their land, such as the Tapus in Gen 7. Their powers go beyond those of normal Pokemon because of these strong links to the elements or to nature as a whole, to the extent that these creatures' actions can shape or reshape the world in many ways.
Some Legendary Pokemon are pretty much deities, not only for the people in the world but in a more literal sense, with prime examples being Palkia, Dialga, and Arceus. Palkia is the god of space, Dialga is the god of time, and Arceus is the literal creator of the Pokemon universe, having shaped the world itself and all Pokemon, including the other Legendaries. Making it easy to fight these Legendary Pokemon already feels strange, as players can simply use game mechanics to best them in battle, but allowing all trainers to catch Legendaries doesn't always make sense.
The lore suggests that humans can only catch Legendary Pokemon because they eventually die, which is when these mythical beasts are unleashed into the wild once more. While the premise does make sense, these are still creatures with no peers and no equals, and seeing how closely tied to the Pokemon universe they are, they shouldn't become mascots on a trainer's adventure. Instead, Legendaries should team up with players for specific quests or even allow players to battle alongside them, essentially not changing what the gameplay of the series is.
On a lore level, this would be a significant change, as players wouldn't simply be able to catch the most powerful creatures in existence with a single Poke Ball or two. It's also worth noting that catching Legendary Pokemon might have catastrophic consequences on the world's balance and ecosystem, and that's why most of the evil teams in Pokemon often seek to control these creatures in the first place. Not every Pokemon game should allow players to catch every single Legendary Pokemon there is for these reasons, and instead focus more on the relationship between trainers and Pokemon.
