For now, a video for killing the Fire boss faster than what TAS does (and a much easier way too). We can kill the boss faster than TAS even though we don't pick up combo upgrades like TAS does! Picking up those combo upgrades wastes at least 36 seconds, probably more for human players. It's honestly not worth it, there's no way you'll ever save 36 seconds during the run by having those combo upgrades. On some bosses having ground combo upgrades only loses time!

Boss has 220 HP, you can kill him easily with following inputs:

• jump and tail spin in the air for 10 damage (210 HP)
• do a 3-hit ground combo to push the boss to the right and deal 42 damage (168 HP)
• jump over the lava pool and tail spin in the air for 10 damage (158 HP)
• land between the lava pool and the boss
• do a 4-hit air combo, followed by air dive (down+right+B) and air tail spin for a total of 82 damage (76 HP)
• repeat the combo above for a total of 82 damage (0 HP)

It's worth mentioning that we're abusing a glitch here. If you do the 4-hit air combo followed by air dive and air tail spin, the tail spin will do 16 damage instead of the usual 10 damage. This glitch only works if you do that specific combo. Thanks to that, we're able to kill the boss faster than what TAS does.

Here's a video comparison between my strats and TAS strats.