I repeated the same basic strategy and won both Ragnaroks again today. I subbed Belphegor for Shiva, but that caused me to eat 2 Rage Overdrives and dragged the fight out unnecessarily. Probably will make Belphegor first support to help with Rage or Stun, should anyone die.
I switched Garuda back in for Medusa and still had Burst generation issues; Burst wasn't ready until Stun. I've found overall that Petrify isn't too much of a problem if you have 3 cleanses; over the course of 3 matches I've never had any characters still Petrified on my attack turn. Obviously you're still at the mercy of RNG (same as with Rahab and debuffs), but with the right layout Petrify shouldn't be an issue in most encounters, even without a team with especially high damage output.