While many Pokemon fans were excited for the announcement of Brilliant Diamond & Shining Pearl, as well as new gameplay information on New Pokemon Snap, the star of Pokemon's most recent direct was the reveal of a new open-world Pokemon game, Pokemon Legends: Arceus.
Taking place during the establishment of the Sinnoh region, the player is sent back to a time long before the events of Diamond & Pearl and is tasked with creating the first Sinnoh Pokedex. While this likely means that there will be a large number of Sinnoh native Pokemon available to the player, there is a lot of room for other regional Pokemon to appear that would enhance the gameplay experience.
Largely due to the Let's Go Pikachu & Eevee titles, Eevee has become something of a secondary mascot to the Pokemon series and has appeared in one form or another in just about every Pokemon game since Red & Blue. In the Generation IV games, Eevee even gained two new evolutions in Leafeon and Glaceon which, while not having as much of an impact as Espeon, Umbreon, or Sylveon, went a long way in letting players evolve their Eevee exactly how they wanted.
Since the draw of Legends: Arceus is the ability to explore an open world, this could also be a good opportunity to bring back the location-specific evolutions from Diamond & Pearl.
9 Nidoking and Nidoqueen
While the Nidoran family didn't make much of an impact in the original Sinnoh games, appearing only while using the Pokeradar on Route 201, they are generally great early-game Pokemon thanks to how early they can evolve and their diverse movepools.
Getting access to powerhouse Pokemon like Nidoking or Nidoqueen early could fix one of the biggest issues with Sword & Shield and allow the player to explore beyond their level while not feeling overwhelmed or held back by restricting mechanics.
Although it made its debut in Gold & Silver, Togepi arguably has a bigger impact on the Sinnoh region than the Johto region, as the Togepi egg returned not only in Diamond & Pearl, but for HeartGold & SoulSilver as a side plot involving the Kimono Girls and Professor Elm.
With the ability to ride around on Pokemon similarly to the Let's Go games being teased around the internet, it would make for a great gameplay experience to be able to jet around the Sinnoh region on the back of a Togekiss.
Unless Legends: Arceus is going to go down the route of the Let's Go games and limit the Pokedex to only those found in the Sinnoh titles (which doesn't seem likely considering Rowlett and Oshawott are two of the starter choices) there will likely be Pokemon from the Unova, Kalos, Alola, and Galar regions in the game.
With this in mind, there would need to be a good reason for them to be there, which is where Hoopa and its portal powers would come in. Similar to its implementation in Omega Ruby & Alpha Sapphire, Hoopa's rings could be used as portals to access new Pokemon from other regions without feeling like the series is retconning which Pokemon lived in Sinnoh.
6 Chikorita and Totodile
One of the strangest aspects of Legends: Arceus is the choice of starter that the player is given in the game. As the Sinnoh region hasn't been inhabited yet, it makes sense that the player won't be able to pick from Chimchar, Turtwig, or Piplup, but limiting the player to only one of the three starter Pokemon from Johto is a little bizarre, especially considering how close Sinnoh and Johto are to one another.
There is also the fact that, while Chikorita isn't seen as one of the better Grass-type starters, Totodile is considered a good Water-type starter and would make a great traveling companion around the lakes of Sinnoh.
5 Litten and Poppllio
Like with Totodile and Chikorita, it stands to reason that the player should be able to gain access to the other two Alolan starter Pokemon.
While Rowlett is a well-loved starter thanks to its design and unique typing, it doesn't have the same clout as Litten, especially in competitive circles, and it would be a shame to only have access to one of these Pokemon throughout the entire playthrough of Legends: Arceus.
4 Tepig and Snivy
The final starter Pokemon for Legends: Arceus, Oshawott, is usually seen as the best choice from the Unova Starters. While Snivy and its evolutions are generally looked at fairly fondly from a design standpoint, they have the same shortcomings as Chikorita when it comes to stats if it doesn't have its hidden ability, Contrary.
Tepig, on the other hand, was widely-hated by Pokemon fans as yet another Fire and Fighting-type Pokemon, a combination that, thankfully, hasn't been used since Unova. That being said, there are still fans of Pokemon who love this fiery pig and should have the chance to fight alongside them in Sinnoh.
3 The Regis
While the Regis are more associated with the Hoenn region, they did get an additional member to their team in the form of Regigigas in the Sinnoh region, which is supposedly the creator of the other Regi Pokemon.
With this in mind, it makes sense to add either Regigigas or the original Hoenn Regis somewhere in Legends: Arceus and may make a decent side quest to track them down, solve their riddles, and capture them.
2 The Lake Guardians
One of the main legendary groups in Sinnoh that should come back for Legends: Arceus, particularly from a story standpoint, is the Lake Guardians.
While many players will overlook Uxie, Mesprit, and Azelf in favor of Dialga, Palkia, and Giratina, they do have quite a large impact on the stories of Diamond & Pearl and they should return for this prequel in a similar capacity, though perhaps without the intervention of Team Galactic this time.
1 The Cover Legendaries
While Arceus is being teased as a major player in the story of Legends: Arceus, its three creations, Dialga, Palkia, and Giratina, shouldn't be left out of the game.
Aside from having the potential to be great boss battles or even simply have questlines attached for the player to track them down, these monsters would be amazing partners to the player when exploring the ancient Sinnoh region.
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