Pokémon adventures for kids? The one where every few episodes a Pokémon gets cut in half? Where Red gets tortured? Where there's, you know, an actual plot? (I've only read the first series, so I don't know if it goes downhill later, but that should be an accurate description of at least the first 3 volumes)
I'm not going to claim it's aimed at adults, but at least it's a lot deeper and daring than the Pokémon anime.
(If you haven't read the Pokémon manga yet, you honestly should, it's what the Pokémon manga (and any other adaptation of Pokémon) should've been like. Although I guess there would've been quite a few more complaining parents...)
This, however, looks like it might have quite an appeal towards kids. Let's not forget that not all popular kids mangas feature kids, and that quite a lot of meant-to-appeal-to-teens mangas often fail miserably but still end up being enjoyable for those who are not mentally capable of understanding how cheesy and ridiculous the dialogues and plot are.
I mean, come on, what teen or older would want to associate with the main character? He looks like what kids think "cool teens" look like to me...