One of the oldest traditions in the Pokemon franchise is choosing a starter. During the first Generation there were heated debates about whether Bulbasaur, Charmander, or Squirtle were the best, and their final evolutions graced the box art for Pokemon Green, Red, and Blue versions respectively. While future titles would feature Legendaries on the cover, that initial starter choice remained. This will still be true for the upcoming Gen 4 remakes Pokemon Brilliant Diamond and Shining Pearl.
Those Kanto region starters set up the pattern of choosing a Grass, Fire, or Water-type Pokemon at the beginning of an adventure. This was clever game design in that it taught players about the rock-paper-scissors metagame for type weaknesses; Fire beating Grass, Grass beating Water, and Water beating Fire. However, it also acted as something of an inherent difficulty slider, with the "easy" Bulbasaur having advantages against the first three Gyms as the "hard" Charmander was weak against the first two. Sinnoh region starters Turtwig, Charmander, and Piplup can similarly be broken down to determine who's best leading into ILCA's remakes.
The Sinnoh Region Starters at a Glance
After meeting Professor Rowan at the beginning of the game, players can choose between the Grass-type Turtwig, Fire-type Chimchar, and Water-type Piplup. All three become dual-type by their final evolutions: Torterra is Grass/Ground, Infernape is Fire/Fighting, and Empoleon is Water/Steel - though Chimchar gains its Fighting-type as soon as it evolves into Monferno.
Torterra's stats make it being a slow physical tank, meanwhile Empoleon is a slow special tank. Infernape's speed is nearly double theirs, and it has equal Attack and Special Attack for mixed strategies. It's also worth noting that Turtwig evolves into Grotle at a later level 18 before evolving again at an early level 32, and Chimchar evolves into Monferno at an early level 14.
One problem with determining the usability of the Sinnoh starters in Brilliant Diamond and Shining Pearl is they're all unavailable in Pokemon Sword and Shield. Because there are no Generation 8 movesets available as of this writing, it's harder to tell which of the three stand out with new moves introduced in the Galar region. Thus it's much easier to stick to discussions revolving around their same-type attack bonus (STAB) moves - those which deal 1.5 times base damage because it matches one of their typings. STAB advantages are particularly important looking at major battles a trainer has to undergo.
Sinnoh's Pokemon League in Brilliant Diamond and Shining Pearl
In every mainline Pokemon game through Sun and Moon, any given region boasted a Pokemon League challenge. These Leagues include eight official Gyms that award Badges to anyone who can best the Gym Leader, and those Badges open up access to the Elite Four and Champion.
The Sinnoh region's Gym circuit begins the same way as Kanto and Hoenn; with a Rock-type Gym Leader, Roark. From there players challenge the Grass-type Gardenia, Fighting-type Maylene, Water-type Crasher Wake, Ghost-type Fantina, Steel-type Byron, Ice-type Candice, and finally Electric-type Volkner. Going by Leader levels in the original Diamond and Pearl, trainers will likely have fully evolved starters by the time they reach Byron, which could be considered the "back half" of the game.
During the first half of Sinnoh's Pokemon League challenge, Turtwig has the most STAB advantages thanks to Roark and Crasher Wake. Chimchar has the most disadvantages being weak to Roark and Crasher Wake, as well as not being able to use Monferno's Fighting-type attacks against Fantina. Infernape turns things around in the back half with STAB advantages against Byron and Candice, however Torterra also has super effective moves against Byron and Volkner in spite of its x4 weakness to Candice.
Piplup may be the most "average" starter to go with in terms of Gyms, but it gets a much better run through the Elite Four. Sinnoh's Elite Four includes the Bug-type trainer Aaron, Ground-type Bertha, Fire-type Flint, and Psychic-type Lucian, with Champion Cynthia having a mixed team defined by her lead Garchomp. Empoleon has advantages against Ground and Fire-types, while resisting Bug and Psychic-type attacks. It's also the easiest of the trio to teach Ice-type moves, making it stand a better chance against Garchomp.
Taking other major trainers into account, Pokemon Diamond and Pearl's Team Galactic boss Cyrus had four partners when battled at Spear Pillar: Honchkrow, Gyarados, Crobat, and Weavile. Empoleon once again has an advantage because of Ice-type attacks and its Steal-type advantage against Weavile, meanwhile Infernape and Torterra both have disadvantages against Flying-types. The rival character Barry's team changes based on what starter the player chooses, so his level of challenge is harder to determine.
Brilliant Diamond and Shining Pearl's Regional Type Breakdown
Another factor worth taking into consideration when picking a starter for the Sinnoh region is its inherent type breakdowns. Pokemon Diamond and Pearl are infamous for a lack of Fire-types, leading to Flint having a particularly strange team. While Brilliant Diamond and Shining Pearl appear to be bringing extra Fire-types from Platinum version over through its Grand Underground, Infernape may still be the best choice if a player is looking to build out a diverse squad.
This is especially true looking at the Grass, Water, Steel, and Ground-type Pokemon available. There's a wealth of choices including Roserade, Gastrodon, Bronzong, Garchomp, Magnezone, and Gliscor to fill the same niches as Torterra and Empoleon. Beyond there being less Fire-types to replace Infernape, there also aren't a wealth of Fighting-types. The Route 1 bird Staraptor can learn Close Combat, but otherwise players only have Lucario, Toxicroak, or Gallade as Fighting-type Pokemon native to Sinnoh.
With all of that taken into consideration, the question of which starter is "easiest" for Brilliant Diamond and Shining Pearl is still tricky. Chimchar is arguably the best all-around choice when team building, but its utility is best in the mid-game. Turtwig makes the early-game easy but plateaus going into the Elite Four. Piplup is arguably the most iconic of the three due to its appearance alongside Dawn in the Pokemon anime, and it is probably the strongest late-game choice. However, it's also probably the easiest to replace, so while Empoleon may stand out most as a Sinnoh starter, ultimately players should choose a partner who best fits their adventure.
Pokemon Brilliant Diamond and Shining Pearl release November 19, 2021 on Nintendo Switch.