Dark Samus 3
The beginning of this fight is extremely easy for each category; you just do the maximum possible damage (or really close to it) that you can do without triggering Dark Samus 4. By category, here are the easiest ways to do that:
- Any%: A super missile plus 4 dark beam shots
- 100%: 25 annihilator shots
- Low%: 10 dark beam shots
Afterwards, she we will do her beam attack either 2 or 3 times. Whether she does it 2 or 3 times is random, and obviously it's a few seconds faster for her to do it 2 times since she comes down sooner.
Initial Screw Attack
Now for the critical part. Try to stay aligned wither her during the beam attacks and a little bit in front of her, to the extent that the top of the screen cuts off around her torso area. Then, as soon as you see her do the animation where she waves her arm cannon down and signals she is going to fall to the ground, do a single jump a little bit to the right (or left) of her, let go of L when you land, and hold forward while pressing B three times to do a falling screw attack beside her. This is one of many ways to setup this screw attack, and if you want then you should find your own method that you're comfortable with. Whatever your method, a really good first screw attack will bring her health bar down to the "a" in "Dark". Anything around the "r" or "k" is still pretty good.
Additional Screw Attacks
As soon as you gain control after your initial screw attack, fire a missile and pull up dark visor to see her. Unfortunately, it is random whether or not she will respond to your missiles and go into Dark Samus 4. This section assumes she cooperates. When she blocks your missile, purposely run into her shield and let yourself get hit. This will put you in hitstun which very temporarily means you can't take more damage/get hit. This is crucial because it means that you are able to go right through her shield in that temporary time frame, since normally it can be very annoying to try and avoid her shield if you don't do this. So, with that said, after you let yourself get hit, you can now freely screw attack right through her shield and pile on damage. Just do a falling screw attack to the side of Dark Samus as you did on the initial screw attack. Ideally, you will kill her on your first additional screw attack (so 2 total when counting the initial guaranteed one). If not, just keep firing missiles, running into her shield, and immediately screw attacking beside her after getting hit. With favorable luck, you will eventually skip Dark Samus 4 and have a good end to your run.
Dark Samus 4
This fight is universal across categories, in that it sucks. It is totally random whether she shoots her "rain" attack or missile attack. Just look up while having your beam charged and wait for the rain. Move a bit forward to dodge her missiles when necessary. When she comes down, the possible damage is capped at a small amount, so a charged dark beam shot or super missile are easy ways to reach that cap quickly. Have fun waiting.