Gawain's Artifice are her burns, which makes your local galactic neighbourhood star look like a brown dwarf in comparison. Your team will quickly turn into a pile of stage girl-shaped cinders if you don't do anything about it. Gawain is immune to MaxHP% DoT. (Yes, I know this has been copy pasted four times. Are you tired of the flavour text? Then stop reading it, fool.)
Anyone that can cleanse or block burn is useful. Merlin Nana, Castaway Kaoruko, and Castaway Hikari, who have burn remove/block are best here. Even though Merlin is at a disadvantage and Castaway Kaoruko is neutral, it's still possible as long as you properly protect them. The much-vaunted Awakened Shiori method is of course no longer viable with the element switch.
1) Flower Nuker + Burn block
First Marie humiliates flower Gawain, and having learned nothing, they introduce the wind version to Marie's flower clone. Castaway Hikari and possibly Kaoruko are also usable in conjunction with Dorothy. Nobunaga Hikari is also usable in this comp.
1) BONK Bonk bonk bonkbonkbonkbonkbonkbonk...
Once again, having learned nothing from cloud Gawain's humiliation at Shiori's twirling or wind Tristan's from Mahiru's bonks, here comes literally the same thing. Same bulk US requirements remain.