Mega Man X2/Deep-Sea Base

Items

 * Sub Tank (need Arm Upgrade & Bubble Crab's weapon)
 * Heart

Stage walkthrough
Bubble Crab is a real cool guy. He lives in a deep-sea base and it's up to you to put a stop to whatever it is he's doing down there.

Head into the cave and dispatch the bats. If you have the Spin Wheel, you can drop it on the rocks to the right to grab a 1-up. If not, take the plunge down the hole into the deep.

These fish move erratically, so hit them with charge shots to ensure a hit before diving deeper. In this large room, you'll be following a huge fish robot. It shines a spotlight back and forth, and if it catches you it'll fire a laser. You can destroy it by shooting each piece of it, but it doesn't make a difference unless there's an X-hunter you want to fight in this stage, in which case destroy it. If you have the arm upgrade, a fully charged Sonic Slicer or two will decimate it.

As the rock path heads downward, the large fish robot will open a large horizontal gate. Instead of heading into the large hole, dash jump over the hole and onto the far right wall. Continue to jump up the wall and at the top, you'll find a small alcove with a life pickup one level up in the cave. To get the Heart Tank, drop back down to the alcove, stop just before the edge of the wall you jumped up prior. Drop down the ledge to wall cling, and then dash wall-jump from the very top of the cliff all the way to the left. Hold down the jump to get maximum airtime. You should see one a vertically moving hover platform. If you're lucky you'll get it when it's at a low point and be able to grab on by wall-jumping, but if not just try again. Jump on top of the platform and climb up the second little alcove to find the heart. Continue back down.

As you fall down the hole, immediately hug the left wall to find a hidden room with blue walls. Fully charge a Silk Shot here to get tons of free life energy - nice if you wanna fill your Sub Tanks.

The big fish will continue lumbering on here, and there's jellyfish to deal with now too. You'll eventually find a different-colored platform, one that looks black and rocky. Go to the center of this platform and fully charge a Bubble Splash. This will make a shield that allows you to jump higher in water. Jump as high as possible to find yourself a Sub Tank on the surface. Wait... Bubble Splash? Isn't that Bubble Crab's weapon? Yes, you'll have to come back to this stage after defeating Crab to get the Sub Tank. You can getit without the Bubble Splash by grabbing onto the left wall and mashing jump to stay on the surface of the water but it's tricky. Continue on, being wary of the floating platforms and jellyfish.

If there's an X-hunter in the stage, either outrun the fish robot or destroy it and go all the way up the right wall to find the optional boss door where the fish would have docked. For more info on the X-hunter system click here. If you don't care, head through the passage on the right wall.

Turrets and screw enemies will line this hallway leading to the Crab. If you have it, use the Sonic Slicer in the shaft going straight up to deal with the wall hugging enemies.

Maverick Boss: Bubble Crab
Bubble Crab! He is slow but powerful and he has a bubble shield. He isn't the most maneuverable boss he for the most part crawls across the bottom of the stage. If you are above him he will stop, lower his shield, and jump up into you. Every once in a while he will fire a bubble ring at you so watch it.
 * Weakness: Spin Wheel

He has another attack that will send a series of bubbles to the top of the room. Inside the bubbles are some smaller crabs in them, if you pop them the little crab inside will home in on you and blow up.

So there are a couple of ways to handle Bubble Crab. If you do not have his weakness you can take advantage of his jump attack because he drops his shield and jumps straight up. What you do is either wall jump over him, air-dash, jump, what ever you do just jump over him. As he drops his shield blast him.

On the other hand, if you do have his weakness Spin Wheel. Release the wheels! It will pop his bubble shield and cause major damage to Bubble Crab.

Bubble Crab gives you the Bubble Splash, which is effective against Flame Stag in the Volcanic Zone stage.