With Skeledirge in a double battle, you can do a maximum of 10912 points of damage, the most possible in the most recent games.
With Sun set up by a helping hand torkoal, 252 sp atk, 31 sp atk ivs, sp atk buffing nature, maximum sp atk set up by spamming torch song onto oblivious Dondozo, Specs tricked on by a Grimmsnarl, set to below 20% health activating Blaze, Using Blast burn onto a Level 1 Snom without any sp def evs or ivs, sp defense lowering nature at -6 sp def, with Fluffy skill swapped from Houndstone and then onto Snom, sitting next to Chi-Yu with Beads of Ruin, the maximum amount of damage possible is obtained.

Note: in the picture i forgot to add sun, which increases fire damage by about 30%.

What about using Last Respects with +6 SpA and all your Pokémon down on a Lv. 1 Ralts with -6 SpD?

first off last respects is a physical move.
and second off fire type just has so many modifyers that make it really strong that the 150 bp Blast Burn is just stronger then 300 bp Last Respects

Ah ok