Bloodborne's story is set in a gothic horror world full of beasts and dark secrets. You play as a hunter trying to uncover the mysteries and survive the nightmarish encounters.
I'm not sure there is an official 'Mario Kart Black Story' in the mainstream Mario Kart series. It might be a fan - made or some very niche concept. So, I can't really provide a definite plot for it.
The top stories can also be about the competitive scene in Mario Kart Tour. There might be stories about top players achieving remarkable feats, like setting new world records. Also, any collaborations with other franchises or events can be a top story. For instance, if there is a cross - promotion with a popular movie or another game, it will surely make the news in the Mario Kart Tour community.
It depends. If you have permission or if your use falls within fair use guidelines, then featuring Mario Kart in fan fiction could be fine. However, without proper authorization, it could lead to problems.