Originally Posted by AssassinDK
Just to confirm, you can actually die during this battle and you will still get the achievement.
Thanks for confirming this, I think the reason to why it didn't work before was because I was playing on Easy, which probably changes the way the achievement triggers.
Unfortunately, I won't be able to finish this guide as both the Wonderswan games aren't as lenient, and there's no continue option that I know of, unless it's unlocked through gameplay. The descriptions should be enough to give an idea of what to do, using videos alongside for some that could give more detail on how to earn them.
If there are any additions that can be added, please post them in this thread and I'll add the info.
Edit: Just noticed that the last message is a month old, I need to pay more attention...