No blood or guts, no guns, no deathmatches, capture the flag, swearing, killcams, perks, XP, etc.
Well, you do kill stuff. Just saying.
Pikmin is very hardcore and not politically correct, because Olimar enslaves the indigenous Pikmin and forces them to kill and be killed in order to find the parts of his space ship. Many hundreds or even thousands have died just for Olimar's self interest. That's about as hardcore as it gets. The game promotes genocide and slavery.
That's by your definition of what "hardcore" means. Personally I define hardcore as a game that you can't just play for a few minutes at a time. Pikmin is a very challenging game which requires hours of dedication. Its not something you can play on your iPad or cell phone while waiting for the bus.