If Crono can use two Lightning-based spells and an ultimate spell that's much more in line with simply being light-based (Luminaire, obviously) as a Light-elemental character, why couldn't Marle use Ice, Ice II and Hexagon Mist? Though if we're making a new Ice-based ultimate magic, I always liked the name Deep Freeze, myself.
And y'all can bash Marle all you want (and ok, I'll admit, Cure II is pretty useless), but I love Iceberg Toss (that is Cube Toss's new name, right?), Ice Sword 2 and especially Final Kick. Always have. That (combined with Crono and Ayla's nice double techs) are why my favorite party is still Crono, Marle and Ayla.
Of course, I also love Crono-Frog-Ayla, Crono-Frog-Lucca, Crono-Marle-Lucca, Crono-Frog-Robo, Magus-Marle-Lucca, Frog-Ayla-Robo and Magus-Lucca-Robo, to name a few. So many good combinations, each with strengths and weaknesses.
And I think I've beaten Lavos with every combination except for most of the ones that don't have triple techs.