An irrelevant factor in terms of what? Because in terms of game design, I call it content. What do you exactly mean by irrelevant factor? I'm interested in this reasoning. Because, as far as I am concerned, Pokémon is fundamentally a game about collecting Pokémon and battling with them, which objectively makes the addition of Pokémon a direct consequence -and need- of what the franchise is about.
Is the adition of 3 Starters irrelevant? I think it is. I mean, the games could go with just 1 starter, isn't it right? How many Pokémon have this new entries? About 104? I think 10 is a good number too. In fact, 0 is also posible. You can do a new Pokémon game with just the 2 new legendaries and nothing new. In terms of story, most of the Pokémon you are going to catch are irrelevant.
That's why I'm so interested. What do you mean by "irrelevant factor"? Non-associated to the story? Guess what, the story in Pokémon is irrelevant and has always been. Pokémon, in itself, being a jRPG, has historically differenciated itself from the rest of the giants of the genre because it lacks precisely what every jRPG is about: story and gameplay. Pokémon used a mix of collectathon, a design usually reserved for platformers (Kirbies, DK64, for example) with gameplay instead of story, and also included connectivity, a factor that is absent of almost every jRPG in existance prior to the MMORPG era, to the point that, in this day, Pokémon is the greatest competitive jRPG of all time.
So, is having 1 less card in a Magic game irrelevant? Is having 1 less tool in your kit irrelevant? I don't think it is irrelevant at all. If everything is "irrelevant", we as consumers are doing a great favor to the companies. If you truly think the memories and experiences derived from the gameplay involved of discovering the existence of Giratina and going to catch it, the first time you reached Rayquaza at the Sky Pillar, or the puzzle and stories derived from Kyurem and his later fight, are "irrelevant" and nonconsequential to a game, we won't understand each other no matter how much we discuss.