Ah. Well, in the most recent version of the game, I've removed the beam attacks and replaced it with the boss shooting missiles into the ceiling, causing blocks to fall down. And overall, the Guardian now relies more on spamming slow normal bullets. I've also redrawn its sprite a bit, so it looks different... I'm not completely satisfied with it yet, though.
Anyway, good suggestion to put ammo vending machines for the missiles, I've not updated them in forever so there's essentially only Machine gun, Hotrod, and Vector Blade ammo to buy. Do you think I need to add machines for both Thunderbolt and Wasp Swarm missiles, or only for one of them?
(Anyway, the improved Guardian will more or less be averagely easy to beat with machine gun and hotrod, since it has shields that blocks attacks from the sides.)
Oh, and if you're playing the old version (so old that the Guardian is still a rock head), the Sun Soldiers does also have a bad pattern that'll be fixed once I get 0.7.3 out and you download it. You'll have to erase your file and start over due to a save file incompitability, but the 0.7 version is worth it, and I daresay it will be months or years before the next file swapping time. Now all arrays are oversized so that I'll practically never run out of flags.