Hello, good to see somebody looking into this game on the TAS side of things. I did a real-time speedrun of this game (currently in the submission queue at SDA), and I still have my notes from when I was researching the game. My route was reasonable barring any tricky skips, but I don't imagine the TAS will be much different without finding any clipping or superjump bugs. Below are some boss values:
Damage:
Sethron 1: 1/4 does 1, 1/2 does 2-3, 3/4 fire does 4 per hit, full does 8, 76 HP
Pterosaur: 75 HP, full flame does 20
Zombie Ankly: 65, kick does 1, bones do 3-12 with full flame; probably same as number of frames connecting with skull
Super Tumor: 72 HP, full flame does 5-6, 3/4 does 2-3, 1/2 does 1-2. Full roar does 18 dmg.
Hell Hive: 65 HP, full does 3-4 per hit, on second volley roar can hit all and do 21 total damage, and kills top left
Last boss has 64 HP, full flame does 5, roar does 8
Boss/Lifebar HP stored in 7E1EED, current value shown in 7E1EE6
7E1E4A - The level of fire. 2 = 1 powerup, 4 = 2 powerups, 6 = 3 powerups, 8 = full
Note that their may be an alternate HP location, as I'm pretty sure those values only refer to the life bar that appears on-screen. It seems silly to program it with the flame doing different amounts of damage on every enemy/boss, so I imagine there are some other addresses being used here and there.
A useful trick for stages 3 and 8 is a boosted jump coming out of the tubes. In order to perform it, you need to land prior to entering (being in the air will result in a tumble motion when you come out) and then just before leaving the tube you have a 2 frame window to jump. This allows you to keep your momentum throughout the jump, and allows for a couple of fast sections.