Zelda can cheese vs ICs, or people who jump a lot, or people who don't get extremely in your face and do frame unsafe stuff. She can also quickly and reliable poke at feet from on any side platform from the ground, or from a drop through. Really, she probably doesn't add too much non-trolly stuff, but I guess reflecting a charge shot with Nayru's love is something?
Honestly, if you're experienced, it's not hard landing tipper fair or bair during edgeguards on Peach, Puff, Falco, Falcon, pretty much any mid or low tier of the low tiers (so long as you can actually reach them), or hitting any of them out of a short hop (fullhop rising fairs make the sweetspot easier at many ranges, if you miss, go to a platform). It's not even hard to do it to Sheik when she jumps or ftilts your shield. Forcing trades with Puff at different heights can also be done reliably.
I guess spaced fsmash can be okay vs shields if the opponent doesn't know what shield DI is, and ftilt or utilt or dash attack to fair or bair can be nice but... Wait, you can do that with Sheik too!
Well, you can do a nair oos that might be better vs the opponent shielding the nair, and even offer you the opportunity to cross them up but, I say only use Zelda if people don't know how to camp her and just try to CC everything or space things in the air really hard, or don't space things at all on in either the air or the ground.