Yeah, I've been trying to do what the guide says, but for some reason I usually lose Veradux or Felicity before I can get the top Guardian's HP down below 20K (the bottom guardian is a little difficult to ignore especially when he casts Enrage one turn and fires that pink thing the next), the other falling soon after, at which point I restart and try again. You certainly weren't kidding about the fight being hard. I think maybe I'll try going for the bottom Guardian first since the top one doesn't do much beyond healing and the basic attack and see if that helps.
My ability bar contains two Mind Freezes, two Flash Freezes, one Glacier, one Shatter, one Guardian Form, and one Ice Wall (though I think I'll probably replace Shatter with Vapor Cannon since the debuffs usually don't last long enough to satisfy the prerequisite for casting Shatter and I'm essentially left without an attack when everything except Shatter and Ice Wall are on cool down).
Sonny
Headgear: Cryptic Helm
Gloves: Hallowed Gloves
Secondary Arms: Blast Shield
Primary Arms: Mending Beacon
Bodywear: Cryptic Armor
Leggings: Cryptic Leggings
Footwear: Cryptic Greaves
Vitality: 341
Strength: 107
Instinct: 617
Speed: 108
Veradux
Headgear: Surgeon's Visage
Gloves: Surgeon's Dexterity
Arms: Law Binder
Bodywear: Surgeon's Shelter
Leggings: Surgeon's Leggings
Footwear: Surgeon's Boots
Vitality: 270
Strength: 257
Instinct: 421
Speed: 224
Felicity
Headgear: Furious Helm
Gloves: Furious Handplates
Arms: Temporal Sword
Bodywear: Platinum Cage
Leggings: Furious Legplates
Footwear: Furious Greaves
Vitality: 277
Strength: 603
Instinct: 145
Speed: 157