Reborn brings together subjects that would normally seem at odds with your traditional pokemon game. Thats not to say its at odds with Pokemon overall however. A lot of the topics are often alluded to in the games, manga and tv show (much less so in the latter admittedly). Each region has a gravesite in all but Johto (who give us a delightful tower that was burnt to the ground, killing the pokemon inside). Cinnabar Island blows the fuck up. Guarantee not everyone got off. Blue's Raticate. And those are just the original games. The Pokemon Wars detailed in X/Y. The first Pokemon movie. Ash was dead guys. He was made of stone, can't get much deader than that. Horrible pokemon experiments in the manga on Misty's Gyarados, Red's Vee, Rhydon's entire existence. Mewtwo's entire existence. Look at all the ghost Pokemon with tragic entries.
Reborn doesn't give us anymore than what is already present in the Pokemon World, it just throws it at us in a fantastically brutal way.