Do any of the others have something like Percy's invulnerability to save them from dying almost immediately due to the skill difference?
well
most of the others are 7A
I'm not entirely sure if their durability works against sharp weapons (since I can't for the life of me find any actual durability feats for any demigod in the Riordanverse besides "comparable to their attack potency" but if they can tank sharp weapons then Elsa can't do anything
assuming they can't, however:
Percy still can't do anything. Water is cool but higher keys don't have invul and he'd need to flood the entire battlefield in order to keep up which not only annihilates the rest of his own team, but Elsa's significant acrobatics and wall clinging and literal wall clinging lets her avoid this anyways
Annabeth also can't do anything cuz she just... has nothing. She's really smart and that's it, meaning Elsa just slices her into ribbons
Piper only has Charmspeak which won't work since it's stated that Piper needs time and significant effort to charmspeak people with Supernatural Willpower (which Elsa has) and Elsa's a woman which means it'll be even less effective
Leo's fire doesn't do anything cuz of regen and heat resistance + he's street level so he just gets stomped
Jason would probably solo by himself. He's 100 times stronger and lightning would probably kill Elsa through her regen, but he kinda needs to vaporize her completely in order for this to work, cuz if he doesn't, he's left omega drained, Elsa regens and kills him
Frank could hold his own due to Blessing of Ares but that just causes a stalemate cuz neither character can hurt each other and once the blessing wears off Frank gets tired and he just dies
Hazel could use the mist to match Elsa's stealth mastery and give setup opportunities for the others to try and kill Elsa
TLDR Hazel needs to trap Elsa in illusions long enough for Jason to zap her, otherwise Elsa just slaughters them all.