Somehow I always end up making Pokemon sound like the best game ever and just tell them what other games that I play that can be compared to Pokemon.
Friend: You still play Pokemon?
Me: Yea, unless you can tell me there is some other RPG that let you choose between 600+ different classes and let you have a party of six I think I will just stick to this.
Friend: Isn't that for kids?
Me: Sometimes I just want to play a casual game. If I want to play something hardcore I would play Nocturne.
Friend: What is Nocturne?
Me: Shin Megami Tensei 3, also known as Lucifer's Call in the UK due to some copyright thing with the name. You know, the game with demons?
Friend: wait what?
Me: You are turn into a half demon yourself when the world ends and you have to recruit other demons to even stand a chance. You can recruit the White Rider, Satan, and some other demons from other religion like Hindu and other stuff as well.
Friend: Dude that sound awesome! (at this point I show him a youtube clip or if he is at my house just play a small example of the game)
Me: Yea but it is kinda hard and it is basically just like Pokemon. I play Pokemon to take a break from this sometimes. Pokemons are pretty much demons anyway, read the dex sometimes. Some of their stuff are kinda dark even for adults. (At this point explain a few like Cubone wearing the skull of his mother, Drifloon steal children, Yamask remembering his past life and cry into his mask, etc.)
Basically I give him something that is already cool (mostly dark & edgy) that he have no choice but to agree it is cool then compare it to Pokemon until he understand Pokemon is just as cool just in it's own way.