I hate it when you beat a tough boss, only to get killed by the Core-X (because you only have a little bit of life left from the real boss). That happened to me after beating SA-X the first time.

The Eye Cores (the ones that give up beam upgrades when defeated) will always shoot you (with the beam upgrade they contain) when they get hit with a missile. So, right after firing a missile at it, you should jump right away.

SPOILER AS TO THE SECOND SECTOR 6 BOSS SPOILER The return of the Security Robot was a pretty hard boss the first time I fought it. Then I watched a youtube video that revealed you can actually hang from the very left end of the ceiling grips, and it can't hit you with most of its attacks. Just the very easy to shoot down homing missiles.
END SPOILER

Done with Nightmare!
I managed to land the last hit with only 11 hp left and the core ready to kill me D:

Now I need to find a nav room asap

If I recall, that's the spot where you're on your own. IF YOU NEED A HINT: Your next target is the red switch.
(and if you can get to a Navigation Room (optional), through some expert-level Shinesparks, you get an extra cutscene where the game will loudly question how many players will actually see it (until youtube was created, not many ) )

OOohh I look for that. Unless it's too late, I'm already trying to kill the SA-X.

Is it just me, or that zombie Ridley was very disappointing? I defeated it in my first try by missile-spamming it.

Nightmare appears.
I'm sure people are exaggerating.
Several tries later.
UUUAAAGHHHH!!!
I finally beat him. Geez

He was ok. Lord knows he's infinitely better than that horrible excuse for a Ridley boss in Zero Mission.

Man, I love the feeling of taking down a boss that always gave you trouble when you were growing up.

I've been re-playing my GBA cartridge of Fusion over the weekend, and 9 1/2 years after first failing, I've finally conquered that jerk Nightmare, and I managed to get to him about an hour quicker and with 50 more missiles, 8 more power bombs and 3 more energy tanks than my original file too. Now I think I might finally beat this thing!

They really really really need to make a 3DS Metroid game! C'mon, Nintendo!

It would probably be another 3D game if they did.

Didn't Retro said they really wanted to remake Metroid II as a 3D sidescroller?
Well, if they really meant it, now it's the time.

Beat the game. That was pretty short, but really fun. Loved it.

Metroids

When did I say that? I'd love to make a video game, period, one day bu- OH. I see what you meant.

I will totally defeat SA-X some day, totally, seriously. One of these days.
... Just a question, how many energy tanks did you guys had by that battle? Because I have like 9 and I still can't deal noticeable damage on that thing.

I had 11 tanks when I beat the game the other night, and I had two or three tanks left after the SA-X fight.

There are 20 Energy Tanks total in Metroid Fusion. I think it's possible to have all but 2 or 3 before Ridley. I know there's one hidden in sector 2 and I think there's one in sector 6 that you can't get before.
I think I might have had 12 the first time I fought Ridley and it was a real struggle.

Wow, it seems my little rest from Fusion to play Metroid II was beneficial, because now I could easily defeat SA-X twice (the omega metroid killed me once) with most of my energy intact (it helps that I found out that her second form can't reach the top-most platform of the room lol)
I beated the game in 4:44 hours (same as Metroid II, creepy) with 50% of the items and the worst ending ... But my 3DS says it actually was 11 hours D:

Loved this (and playing II and watching all the cutscenes from Other M in youtube made it even better). I never really cared about the series before, but now I'm a fan.
I'll try to get a better ending next time >:3

Yeah, my experience was similar. Never really into the series before, but now that I've played II & Fusion on my 3DS, I want more (if they ever put GBA games on eShop, I want Zero Mission).

If they ever release Zero Mission and/or Super Metroid for the 3DS VC I'll be very happy.