Sorry to keep posting here but I got another question. What inputs do you put in to get so many attacks out in a short period because I'm having trouble on the bridge since I can't kill the guy quickly and I know this will continue to be a problem. I tried just watching some of the runs but it all happens to fast for me too recreate.

The first thing I will say is that double hits are an advanced technique and while they do save time are not required to be able to complete a Zelda 2 speedrun in any category. For example, runner cantaloupeme has a 1:16:32 (currently 15th place) in 100% All Keys and he does not use double hits at all.

Generally I recommend people get comfortable with fighting red dairas (the ax throwing enemies) with falling crouch stabs before worrying about double hits. Yes, this is slower but it also helps with learning how to read the daira to know when it's safe to attack and when it's not. On the bridge you have an extra challenge of dealing with the bubbles and the red daira at the same time - this is not an easy fight at 1-1-1 levels, even if you've speedrun other categories before.

As for the inputs required to do these double hits, I'll start with describing the actions in game language and then translate to what the buttons are. The red daira reads your d-pad, so it helps to let off the d-pad while jumping (your momentum will keep your motion in the air), this lets you get closer to the enemy. You need to be very close for the second hit to land. So when you jump, release the d-pad and do a falling standing stab, then when you land, you want to immediately do a rising crouch stab. To translate this to actual inputs - when you're walking, jump with A and release the d-pad. As link is falling press B to stab the enemy. Once link lands, immediately press A and hold Down on the d-pad to jump and crouch, very quickly after that press B to do the crouch stab. If you're close enough to the enemy and you did the inputs correctly, you will land a double hit.

When it comes to chaining multiple double hits together back to back, this using the same method as above, but managing your distance from the enemy with left or right on the d-pad and can take some time to get the hang of.