Well trainers do have a massive impact on how people perceive pokemon aswell. Lillie entire arc in both games SM/USUM presents the evolution of cosmog to Sungaleo/Lunala.
Cynthia’s surprise from a hook from the start with her spiritomb with her massive finisher garchomp at the end.
Zinnia and Rayquaza having massive lore ties since the ORAS remakes.
N’s final fight in BW with Reshiram/Zekrom
Any pokemon as an Ace/tied lorewise of a highly known trainer is bound to help with popularity.
I think purely TCG collectors live in a bit of a bubble.
If you don’t play the TCG, play the video game or watch the anime, you don’t develop relationships with new Pokémon. This applies to the majority of purely card collectors. It’s hard to look at a new Pokémon and develop a connection with them if you haven’t used it in battle (TCG or VGC) or seen it in battle (anime).
I’ve lived in Japan and now currently in Taiwan and yeah, the kids aren’t playing solely with Gen 1 plushies. The newer Pokemon are quite popular here because there’s tons of avenues for their relationships with new Pokémon to flourish. You can even develop your relationship with Pokémon via vending machine toys, candy and other misc merchandise (including toilet paper 
).
Also there’s something to be said about years of exposure. Mickey Mouse will always be more iconic than Buzz Lightyear. But Buzz Lightyear will always be more iconic than Nemo. It’s not that one is necessarily better than the other but that length of exposure is very important for a character’s popularity.
Yeah, some, maybe even a lot of people, really need to read/listen/accept this.
Wonder why do some people always assume the worst… 
100% agree with 4thstar that time is a big factor along with consistent and strong representation of a Pokémon over time.
It can be difficult to draw parallels between the Pokémon in the current most-popular list because there are so many possible things that can influence popularity. However in general I think it’s that the designs aren’t too complicated nor do they stray too far from popular real or mythological creatures, and have recurring forefront representation in the anime and video games. Charizard, Rayquaza and Dragonite are all clear draconic representations, dragons have never not been popular. In the games they’re not just cool but all rewarding Pokémon to own. Pikachu, Eevee and Umbreon on the other hand obviously draw from the classic cuteness of the small rodent/feline, but again maintain simplistic and cute designs. As Knotchi points out, they’re easier to form an organic connection with.
As far as the most popular Pokemon being limited to Gens 1-3, again it’s down to time, but also the fact that early on the IP had so many creatures to work with; “rookie” representations of animals that most people in the world can resonate with; cats, dogs, mice, rabbits, birds, dragons, dinosaurs. Now that most species have been represented, later generations have really faced the challenge of novelty. Now we’re looking at furniture and skyscraper-based Pokémon! That said, I fully believe there’s plenty of room for them to expand on existing species, and if done well then absolutely still room for new entries in the top-ten list.
You’re literally just a pig.