No Damage analysis
Lowest damage analysis (for PAL and NTSC, inbounds, without Spazer+Plasma beam combinations):
The lowest amount of damage to Samus´ health that can in total occur such that the game can still be beaten (even by players without the use of tools) is exactly 300 (caused by a single Rainbow-beam by MotherBrain 2 if and only if Varia was collected and is kept on during the entire Rainbow-beam to cut 600 damage down to 300 damage).
In order to beat the game this way without taking more than 300 damage in total, Gravity suit is needed since Samus starts with (99 health and in particular) more than 00 health, and either lava in Norfair (in the Gravitron room, also known as the lavapit) has to be entered and there it cannot be prevented by any known means to avoid taking damage without having the Gravity suit turn on, or one would need to avoid the lava by taking the reverse Lower Norfair route for which one has to take damage aswell for the required setup that needs to be used to be able to use this alternative path (so that this path is not a viable option in any case). The Gravity suit is not part of any of the known five 13% branches that are available to tool-assisted superplay, which means under Low% conditions one would need to take at least 14% of the available items (which is a sufficient amount to beat the game under the above requirement of taking as little total damage as needed).
Furthermore, in Low% conditions either sufficient ammunition (to kill all Zebetites) or Ice beam is necessary for getting past the Zebetites without taking damage (which can be achieved by spinjumping into the first Zebetite in order to gain temporary invincibility without losing health since the Zebetites as solid (non-moving) enemies do 0 contact damage). In particular, a spark will cost energy in any case and is hence not a viable option.
In the case of trying to obtain enough ammunition in order to get rid of all Zebetites, one could not make use of the Draygon ammunition Underflow because this would require taking additional damage (outside of the required damage) in order to execute a Crystal Flash.
Since 14% is a sufficient amount of items for the alternative case in which one takes Ice beam in order to get past the obstacle that the Zebetites constitute, one would not be allowed to surpass 14% in the case of destroying all Zebetites. With (1*M, 3*SM), one would lose at least 2 Super Missile projectiles per Zebetite and end up with 5 Missiles and 7 Super Missiles remaining for Mother Brain 1 and the glass tank which isn't enough (already due to the number of projectiles being strictly less than 18 which is the minimal needed amount to entirely break the glass tank). With (2*M, 2*SM), one would lose at least 1 Super Missile projectile per Zebetite and end up with 10 Missiles and 6 Super Missiles which is again not enough for the rest. With (3*M, 1*SM), one could get rid of all Zebetites without losing any Super Missile projectiles, however 15 Missiles and 5 Super Missiles together are 600 damage too little to get past Mother Brain 1, and if one would first destroy just the glass tank and come back with full Missiles, then the remaining 15 Missiles and 2 Super Missiles wouldn't allow for enough damage on Mother Brain 1 either. Hence the amount of Missiles together with Super Missiles would take up at least 5 items (since any viable combination of 4 items among these 2 types would be insufficient) if one needed to kill all Zebetites and needed to beat the game in such manner. Together with the core of items that would be part of any such playthrough of the game (refered to as Core and given explicitly below) that doesn't use the Draygon Underflow, the situation (in the case of skipping Ice in favour of killing all Zebetites) would already result in strictly more than 14 items being collected if one necessarily adds 2 more Tanks and Gravity suit to the 8 items from the Core, and then considers at least 3 more items towards the amount of Missiles and Super Missiles from the Core aswell as at least 1 final additional item being needed in order to get to Draygon (either through pre-Botwoon room or Plasma beach room).
Thus, the set of all 300Damage-Low% options is given as follows:
The core of items that all 300Damage-14% branches share (and have in common) is given by Core = (Ball, 1*M, Bomb, 1*SM, 1*PB, E-Tank, Varia, Charge). All available different corresponding branches are listed below:
Gravity-Ice:
(Core+1*M+1*SM, Gravity, Ice, 2*E-Tank) ;
(Core+2*SM, Gravity, Ice, 2*E-Tank) ;
(Core+1*M+1*SM, Gravity, Ice, 1*E-Tank, R-Tank) ;
(Core+2*SM, Gravity, Ice, 1*E-Tank, R-Tank) ;
(Core+1*M+1*SM, Gravity, Ice, 2*R-Tank) ;
(Core+2*SM, Gravity, Ice, 2*R-Tank).
For players without tool-assistance, the lowest amount of items for 300Damage-Low% arrived at the limit of 14%.
300Damage-Low%:
https://www.youtube.com/watch?v=sikwMkteTRA&t=0s&list=PL5If8zSOO37bqYjqONhUSBfYDgaDIrcP6&index=9
https://www.youtube.com/watch?v=BywbMgiVHqw&t=0s&list=PL5If8zSOO37bqYjqONhUSBfYDgaDIrcP6&index=10
https://www.youtube.com/watch?v=upBHAp_p-y0&t=0s&list=PL5If8zSOO37bqYjqONhUSBfYDgaDIrcP6&index=11
https://www.youtube.com/watch?v=0zcw6IgDT7g&t=0s&list=PL5If8zSOO37bqYjqONhUSBfYDgaDIrcP6&index=12
and
https://www.twitch.tv/videos/126639181
https://www.twitch.tv/videos/126639814
(these are so far the only known completions of this type).
The unique 300Damage-Max% option consists of all items except (14-5)= 9 E-Tanks (since otherwise MotherBrain 2 will add further attacks with onions and bombs if Samus' health is strictly more than 299 after the first Rainbow-beam even if Varia was turned off appropriately right after the Rainbow-beam ends), hence the maximum is 91%.
300Damage-Max%:
https://www.youtube.com/watch?v=4JAf4B1qIO0&list=UU5M90zTdMDWQpxnCgcIuoRA]https://www.youtube.com/watch?v=4JAf4B1qIO0&list=UU5M90zTdMDWQpxnCgcIuoRA
https://www.youtube.com/watch?v=w7gIdFEjJmg&list=UU5M90zTdMDWQpxnCgcIuoRA]https://www.youtube.com/watch?v=w7gIdFEjJmg&list=UU5M90zTdMDWQpxnCgcIuoRA
https://www.youtube.com/watch?v=UpPoHLcLFxs&list=UU5M90zTdMDWQpxnCgcIuoRA]https://www.youtube.com/watch?v=UpPoHLcLFxs&list=UU5M90zTdMDWQpxnCgcIuoRA
https://www.youtube.com/watch?v=A3J9_7EYYG8&list=UU5M90zTdMDWQpxnCgcIuoRA]https://www.youtube.com/watch?v=A3J9_7EYYG8&list=UU5M90zTdMDWQpxnCgcIuoRA
