I have seen too much confusion about this here and everywhere and I believe it's time to set things straight. Yes, Pokémon Let's Go, Pikachu! and Let's Go, Eevee! are core series Pokémon games. They are also mainline game. Mainline and core is exactly the same thing. Pokémon Let's Go is the third entry in the seventh generation of core Pokémon series. And will be remembered as the first core Pokémon game ever on a home console. Now, allow me to explain. Pocket Monsters To explain this I first have to talk about the origins of Pokémon. ポケットモンスター 赤 Pocket Monsters: Red and ポケットモンスター 緑 Pocket Monsters: Green were the first games of the entire Pokémon franchise, released on 1996. The Pocket Monsters franchise was brought to the west as the "Pokémon" franchise, a smaller one-word name because Pocket Monsters is a mouthful. After this they also begun to use the term "Pokémon" in Japan and nowadays every Pokémon movie starts with the phrase "Pocket Monsters, or Pokemon for short". On 1998, thanks to Pokémon popularity, the first ever spin-off title (as we categorize them here on the west) was released: ポケモン スタジアム Pokémon Stadium for the Nintendo 64. At the time developers didn't want people to confuse spin-offs with the main Pokémon series, so they decided to use the short word "Pokémon" (ポケモン) for every spin-off game since while reserving the full name Pocket Monsters ポケットモンスターシリーズ for the main series. In Japan the official term Game Freak uses for spin-off games is 『ポケットモンスター』シリーズ 関連作品 which in English would be "Pocket Monsters series related games". On The Pokémon Company's website the term used for spin-offs is そのほかのポケモンソフト or "Other Pokémon soft". Core games For years the term "mainline games" or the "main series" were used by fans to refer to the main Pokémon RPGs for Nintendo handhelds. The term was also used loosely by Nintendo and TPCi however that changed on the 5th generation. You see, for years The Pokémon Company International was using incorrect or at least not totally accurate translations for some aspects related to the games. One of these aspects are Legendary Pokémon. Spoiler: Appendix about the Legendary/Mythical confusion In Japan since Pokémon Red and Green there have been two groups of very special Pokémon: 伝説のポケモン Legendary Pokémon and 幻のポケモン Illusory Pokémon. Legendary is the group of powerful Pokémon that can be caught in-game and are usually the ones in the cover like Mewtwo, Groudon, Rayquaza, Dialga, Giratina, Zekrom, Xerneas, Zygarde, Tapu Koko, Solgaleo, Lunala, Necrozma, etc. On the other hand, the Illusory group was created so developers could hide Pokémon in the game data and then distribute the creatures themselves as a later date as a way to revive hype for the game. The first Illusory Pokémon was Mew, and since we have lots of event-exclusive Pokémon such as Celebi, Jirachi, Arceus, Genesect, Volcanion, Zeraora, etc. However, when the games where brought to the west the translators ignored this difference and called every Pokémon from both groups "Legendary". This mistake continue to being carried for years until TPCi decided to stop it and in Gen V the official translation of "Mythical Pokémon" was used for the first time. Ever since Pokémon BW, official media in the west recognizes the two separate terms and Mythical or Illusory Pokémon were never referred to as Legendary again. Another translation that was corrected, or at least they started to take it more seriously is an official designation for the mainline Pokémon games. Both spin-offs and mainline games are called "Pokémon" here so they couldn't suddenly change the games to "Pocket Monsters". However they decided that the official term for the mainline series would be the "Core Series". The earliest use of this term that I could find was on an interview with IGN where they ask if the mainline games will ever be on a home console like the Wii. The interviewer of course has no idea that the "core series" term exist so it's normal to use the mainline term. However, when replying the Masuda's translator uses the correct term core series. Since then, The Pokémon Company International has always referred to the main Pokémon series as the "core series of Pokémon RPGs". During Generation 6 the term gained more notoriety as it was used for X/Y on an Iwata Asks interview and also on the official website. Pokémon Let's Go Now we're finally back to 2018. As you should have learned through this post, the difference between "core" and "mainline" doesn't exist in Japan. There there are only two very clearly defined categories of games, the "Pocket Monsters series games" and the "Pokemon games". The official Japanese names for the games are ポケットモンスター Let's Go! ピカチュウ Pocket Monsters: Let's Go! Pikachu and ポケットモンスター Let's Go! イーブイ Pocket Monsters: Let's Go! Eievui. They are both part of the Pocket Monsters series. Tsunekazu Ishihara, TPC's president, stated very clearly in the Famitsu interview that Pokémon Let's Go are the first Pocket Monsters series games ever on a home console. And as you saw on the Twitter video on the top of this post, throughout the conference the games were called mainline / core multiple times. The reality is that core and mainline is exactly the same thing. There's no difference, both are translated exactly the same to "Pocket Monsters series" in Japanese. Even Joe from Serebii had to clarify on Twitter yesterday about this: Let's Go is a very different game from previous entries in the core series sure, and the next game will be very different from it, but that doesn't mean Let's Go isn't part of the core series. Some people try to undervalue Let's Go by saying it's a spin-off or that it isn't a core game, but those are just lies. Not even an opinion: a lie. Something not true. The 2019 core game Now let's briefly talk about the core Pokémon RPG for 2019. This will be the first game from the eight generation of Pokémon and the second entry of the series for a home console. Many people refer to the tweet from TPC to say something like "the true core game will be out in 2019 and Let's Go is a spin-off" but that's misleading. Yes, the 2019 game will be part of the core Pokémon series. A new core game is coming in 2019. However, that doesn't mean that Let´s Go is not a core game. Heck, as you saw in the video above in the press conference they explicitly stated that the 2019 title will be "another core game", apart from Let's Go. Both are core games. If you are reading this then that means you (hopefully) have read everything until the end! Thank you for taking your time. I hope my post helps to clear some of the confusion about Pokémon Let's Go, Pikachu! and Let's Go, Eevee! Of course you are free to have your own opinion of the games, you can even hate them if you want, but please don't spread misinformation. The fake news problem is already very bothersome, let's not make it worse. Even though the games are clearly not oriented to our "hardcore" demographic, I applaud Game Freak for finally experimenting with the core series and trying something new, as they are known to be very safe and predictable. Let's hope that the next time Game Freak decides to take a big risk they focus on longtime Pokémon fans.