Argh!!!!!! Man, I tell ya, this game is a true gem. That final boss though is pure hell!!!!
Alright, earlier today I killed the orbs section (somehow). But I only had 1 hit left, and the final form (I hope its the final form) blasted me right off the bat.
Later, I figured out that killing each individual part of the bosses yields LOTS o' points. I went from being level 11 at the final level to being level 13. I almost had the final boss this time too (I switch over to the super powerful green shot throughout the final level... its the only way...) as I had over half of my life going into him and an almost full special attack bar. So I dropped a bomb upon approach since it kills off two orbs and weakens all but one to an easy enough state to finish off.
And wouldn't ya know, the last orb standing was the yellow one. Thats right. Lightning attack. Any time I lined up to take it down, thousands of volts into ye old Zeroigar. Needless to say, the yellow orb wiped me out.
So, advice for anyone going up against the final boss of Zeroigar: Kill the yellow orb first. Yellow and red throw out the hardest to dodge attacks, the rest of them are simple enough.
I have no clue about the final form of the boss though. I didn't survive long enough to witness his attacks. Hopefully he isn't harder than the orbs though, without a bomb those things would be HELL.
Love the game though. Excellent music and the boss fights are pure class. The levels are kinda boring though... except for the mid-boss fights. Especially the "rival" mech, those fights are awesome. Though I hate the final fight against the "rival" mech. Those half-moon shots are hell. If you're having trouble, use the flame thrower when he's about the launch those, as it'll kill any shots it hits and give you more dodging room. And keep in mind:
First attack: Triple laser.
Second attack: Lightning Storm
Third Attack: Lightning Storm followed by triple laser.