Move 1: Temper Flare
2:Last Resort
You'll need only the two moves above so for the latter two moves, pick what you want. I usually go Sunny Day + Detect
Item:Toxic Orb
Ability:Guts
Extras: Grassy terrain + Sun is helpful .
Tera:Fire
Nature:Any atk boosting nature will work but I like Adamant
First turn Flare is on the field, use Last Resort. Due to the mechanics of the move, it will fail and thus power up Temper Flare.
Next turn the guts boost will kick in through the toxic orb, use Temper Flare and perhaps tera (but not needed) STAB physical fire move (bonus points if sunny) at your service
Bonus points if this is doubles, trick the sitrus Berry or leftovers onto flareon, triple points if the trick mon has magic guard
2:Last Resort
You'll need only the two moves above so for the latter two moves, pick what you want. I usually go Sunny Day + Detect
Item:Toxic Orb
Ability:Guts
Extras: Grassy terrain + Sun is helpful .
Tera:Fire
Nature:Any atk boosting nature will work but I like Adamant
First turn Flare is on the field, use Last Resort. Due to the mechanics of the move, it will fail and thus power up Temper Flare.
Next turn the guts boost will kick in through the toxic orb, use Temper Flare and perhaps tera (but not needed) STAB physical fire move (bonus points if sunny) at your service
Bonus points if this is doubles, trick the sitrus Berry or leftovers onto flareon, triple points if the trick mon has magic guard