Man, this is such a specific crossover niche, but you see it popping up in the 'Naruto visits other worlds' collections sometimes. The number one trope is definitely 'Naruto replaces Yusuke Urameshi'. The premise usually goes that after Pain's assault or the war, some dimensional screw-up sends him to the 'Yu Yu Hakusho' world, and he ends up entangled with Team Urameshi, with Shizuka as the obligatory 'normal' person who has to deal with this loud, orange-clad ninja suddenly living in her house. It leans heavily on the 'fish out of water' comedy and Shizuka's exasperated but kind-hearted caretaker vibe from the original series.
A close second is the 'found family' theme, but with a twist. Since Shizuka is essentially Yusuke's adoptive mom, writers often explore Naruto filling a sort of 'older brother' role to Yusuke, which creates this weird dynamic where Shizuka ends up as a maternal figure to Naruto too. You get these surprisingly soft scenes of her patching up his wounds or making him ramen, which hits different because Naruto's own childhood was so devoid of that. It's less about romance and more about healing that lonely-kid trauma through an unexpected connection.
Some fics try to age Shizuka down or Naruto up to force a romantic pairing, but honestly, those rarely work. The appeal isn't really in shipping them together; it's in the contrast between Naruto's hyper-active, battle-hardened shinobi life and Shizuka's grounded, mundane reality. The best fics use that to have Naruto learn about a peaceful life, while Shizuka gets a crash course in the insane sacrifices heroes make.