Chozo Statue-1:
The Chozo Statue holding the bombs is pretty much a midboss for 
Crateria.  After you remove the bombs, he stands up and spreads bombs 
across the floor.  He also swipes at you with his claws.  Avoid his 
claws and bombs, while shooting him in the chest with your gun, or 
missiles.  If you get low on energy, or insist on using only missiles, 
destroy the bombs he throws at you.  He'll be almost dead after his 
head blows up.

Spore Spawn:
This plant-like creature is somewhat circular.  He swings around and 
tries to hit you while he sprinkles spores from the ceiling.  To beat 
him, crouch into a ball, roll into a corner, and avoid his spores.  
When he opens his mouth, jump up and shoot missiles into it.  If you 
run out of missiles, shoot the spores, which will turn into energy or 
missiles.

Kraid:
Kraid is the final boss of Brinstar.  He is large and very similar to 
the miniature you face before you get to him.  To defeat him, shoot a 
missile at his stomach and shoot super missiles into his mouth.  Repeat 
this procedure until he is dead, but watch out for his claws, which 
return to him after he has thrown them.

Crocmire:
Crocmire is just like Kraid.  Shoot missiles at him to open his mouth, 
and into his mouth to drive him back.  Keep doing this until he falls 
into the lava.  When his skeleton appears, don't waste missiles.  The 
skeleton just falls apart.

Phantoon:
Phantoon is the really tough boss of the Wrecked Ship area.  Make sure 
you have as much energy tanks as possible, and get all the missiles you 
can.  When he isn't solid, he throws fireballs at you, which can be 
shot down.  When he is solid, and has his eyes open, he appears and 
shoots a ring of fire.  Brave the fire and shoot super missiles into 
his eye as long as it's open.  Defeating him restores power to the 
whole ship, but also turns on some enemies.

Botwoon:
Botwoon is the midboss for Maridia.  This aquatic snake shoots at you 
while dodging between his holes in the wall.  Be quicker than him and 
shoot super missiles at his head.  If you do, the battle will be over 
soon.

Draygon:
Draygon, a creature that looks like a crayfish, is the boss of Maridia.  
In his room are four energy cannons.  Destroy them and Draygon will try 
to pick you up.  Use your grappling beam to hook up to one of the 
destroyed cannons and Draygon will be quickly electrocuted.  This leads 
to several important items.

Chozo Statue-2:
This statue doesn't give you anything before attacking.  Only super 
missiles can hurt him, so stock up on them.  You can shoot them at him 
from behind, or you can shoot repetitively at him from his front.  
He'll catch missiles fired at his front, but can only catch one at a 
time.  Dodge the missile, him, and his projectiles to stay alive.  If 
in need of energy or super missiles, shoot his projectiles.

Ridley:
Ridley, a giant flying reptile, is the boss of Norfair.  He appears in 
the Space Colony, but leaves when you lose about one third of your 
life.  His main tactic is to spike you with his tail.  When he is about 
to do this, roll into a ball, and lure him as far to one side as 
possible.  Then go under and behind him and shoot him in the head with 
super missiles.  You have to watch out for his fireballs though.  When 
he is about to swoop, jump the opposite way in a spiral jump, which 
will protect you from when you brush up against his body, but not his 
tail.  If he only swoops half way, jump and get a shot in.  Do this 
until he's defeated.  

Metroid Matrix:
Don't worry about him.  Let him drain you all the way to zero energy.  
Then he'll hesitate and leave.  Continue to the left, go down the 
passage and into the left door, and you'll be able to recharge energy 
and missiles.

Mother Brain:
When you enter his chamber, it's like in the first metroid game.  I 
used super missiles to get through the barriers.  Otherwise, the turret 
guns will eat you alive.  When you get to mother brain, break the glass 
and shoot any missiles you can at it.  When it flies backward, it's not 
dead.  Mother Brain's new trick is a new body.  It turns into a huge 
monster.  You need to shoot it in the head with missiles, a Charged 
Plasma Beam, or a Charged Spazer beam.  His attacks include an eyebeam, 
which is meant to knock you down.  Watch out for the blue energy balls, 
they take off a lot of energy.  The bombs it drops aren't regular 
bombs.  When the bombs go off, get off the floor entirely.  After a 
long while of getting pounded, mother brain will unleash a powerful 
hand beam.  DO NOT TOUCH THESE BEAMS.  If you touch them, they drain a 
TON of energy.  Shortly after that, Mother Brain will use mind blasts 
until you are severely weakened.  Then, unexpectedly, the metroid 
matrix comes in and attacks Mother Brain.  The matrix weakens Mother 
Brain severely, and then restores your energy to maximum.  While he's 
restoring your life, Mother Brain sneaks up on him and destroys him.  
The matrix hovers above your head, and explodes into a sparkling dust, 
which falls on you.  This gives you a beam of incredible power.  Shoot 
this repetitively at Mother Brain, avoiding his attacks, and you'll 
easily dust him.  After defeating him, get to you ship FAST!!!!!!!  Use 
the opening behind the defeated Mother Brain!