For 3* Shiva, I used Basch, E.Marie(Ifrit), LM Fina, and E.TT x2, all with 60% ice resist or higher.
Turn 1: Lovely Guard +1, Dawn Guard, Manatopia, Maudin Guard, Guard
Turn 2: magical activation x2, Love You All+2, Basch's SPR break, whatever with LM Fina
Turn 3: Chaos Wave (Awakened if available) x4, keep buffs up
Repeat turn 3 until Diamond Dust, at which point LM Fina dualcasts Dispelga (using the target trick to put one on your own party) as your first action of the turn and you restart from turn 1.
The hardest past of the fight with this strategy is getting the target trick to work 3 times.