Well, I started a TAS for this, but I officially give up. Just figured I'd share some information in hopes that someone else will complete this run some day:
-Get both the Wet Suit and the Rocket Suit from the mid-level bosses in stage 2 and 3.
-Selecting a different stage in this game takes several seconds (as seen from 0:30 to 0:38 in
this video). Still, you should do them in this order: 3 - (1/2) - 4 - 5 - 6. The Rocket Suit you get in stage 3 will save you quite a bit of time in stage 2, especially in area 6 (as seen from 3:00 to 3:10 in that video) where you'd have to wait one more time for the fire to rise and fall without the suit. That alone more than makes up for the time it takes to select stage 3 before 2. It doesn't matter what order you do stage 1 and 2 in, as there's no water in stage 1, but I am about 99% sure that doing stage 1 after stage 3 will save you time, mostly because your attacks are more powerful with a power suit on, which means the boss fight will be faster, but also because there are a couple of areas were flying is faster. You might want to test this more thoroughly than me, though, to be 100% sure.
-Slide whenever possible. Sliding is faster than flying with the Rocket Suit, and it's faster than swimming with the Wet Suit. Sliding is faster with a power suit on, so the only times you should unequip the power suits are in auto-scrolling areas.
-The item drops from enemies are solely based on how many enemies you've killed before. The first enemy you kill in the game will always drop a small battery, and the tenth enemy you kill will always drop a red boomerang, for example. Note that if you leave a screen too early after you've killed an enemy, that enemy won't "count". The "exploding" animation has to end before you leave the screen.
-You probably need to pick up all the big batteries you can get to (there's one that's impossible to get without the Newt Suit), but you'll have to test this yourself, I'm afraid.
-Get a red boomerang by killing ten enemies before the mid-level boss in level 3. You'll obviously use a power suit for all the other bosses.
And that's all I've got. Hopefully this will be somewhat helpful for whoever might try to TAS this game sometime in the future.
BTW, here's my stage 2 WIP:
http://dehacked.2y.net/microstorage.php/info/1999227460/Power%20Blade%202%20WIP%20BZero.fcm
Yes, I started on stage 2 before finding out that I would save time by getting the Rocket Suit as well and that I would save even more time by getting it before doing stage 2. This WIP ends after area 6. You'll see that I make sure to get a red boomerang before the mid-level boss. I actually have to wait 1 extra frame before leaving the screen at the end of area 1 to make that last enemy I killed there count. You'll also see "slide whenever possible" in action right after the mid-level boss.
