What is a good strategy for defeating groups of Galvanades?

I have completed this dungeon and these enemies prompted me to have a search around.

The technique I used was to cook up some Dual-Cast or better Blizzara, to open the fight with and then to use Gladio's abilities, either Cyclone or Dawn Hammer, which will cause them to flinch.

Then it's a matter of prioritising them as quick as you can, if you have Tech Bar boosting items, you can use Ignis' Overwhelm ability. If you can kill or stagger them, they won't explode, thus not spawning the additional mobs.

Gamersheroes recommends,

Galvanade (Level 54) Weaknesses: Royal Arms, Guns, Machine Weapons, Blizzard
Notes: If you take too long to kill these they summon lots of Thunder Bombs. Dawn Hammer works to take them down quick.

Other techniques people have used, also work with your bros abilities.

Promto+graviton shot+killcast 99 blizzara=gg move on.

Also worth cooking a meal which helps with elemental resistance.

.. the meal you can get at Galdin Quay that negates elemental attacks - crab something or other. Costs about 3000 gil