The cores are protected by barriers. Shoot away at them till the core is revealed.
Watch out for the rollers as you attack the core.
Like in Area 2, the electric barriers won't kill you but you will be stunned.
These four cores can be destroyed only while crouching.
The first two are revealed in the middle then the other two will open on opposite sides.
Be wary of one of the enemies throwing rollers around.
You got two barriered cores in the next room.
Once the barriers are gone. Take on the these cores. Ignore the cannon on top.
The next room has two cores you can defeat while crouching which makes this room quick.
The cores are on opposite sides of the room.
Aim at the core in the middle and that's it.
This one is a tricky one. Kill the cannon first.
You have to jump to shoot the core. Watch out for the enemies throwing grendades. This is their answer to you crouching under their bullets.
Three cannons and the mega core. Take out the cannons first then concentrate on the megacore.
The boss battle starts off just like in Area 2 except there is one cannon and three cores.
Destroy the middle core then target the cannon.
During the battle enemies will appear and try to throw you off by jumping down at you.
They also come in blue variety too.
When you defeat all cores. The main boss appears.
The bosses each split in two but I'll give you a brief lesson in anti-limitation tricks.
As you can see in this screenshot there are still two bosses but in the game itself there are actually four because the bosses and their clones' sprites flicker back and forth so rapidly that you see them spliting up then merging back to two. Attack them when they are merged together to damage them but watch out for the nuclei bubbles that are hard to avoid because they move in odd directions.
Once you defeat one, defeat the other to finish the level.