Most of Bubble Crab's stage takes place underwater. Robots can't drown, but apparently they are a bit buoyant, since you'll be able to jump much higher than usual. You'll meet a new old enemy right off the bat.
Get it? Bat?? *ahem* These guys have been around in some form or another since the original series. They float around and go down with a single shot. Simple.
Proceed right and jump over the hole for now. Use the Spin Wheel to destroy these blocks and get to the 1up. Then jump down the hole and into the water.
A new environment means new enemies. These fishies quickly swim left and right, sometimes ascending or descending. They have low HP but they generally appear in schools and find strength in numbers.
There's a small health pickup to the right. Head left and down, deeper into the water. Time for a miniboss. Kind of.
This big fishbot is made of multiple parts that can all be destroyed individually with enough damage. It will swim through the level, firing torpedos. If it catches you in its searchlight, it will fire a sweeping laser beneath it. You can destroy its fins and light with any weapon, especially the Sonic Slicer, which it's weak to. Use the Sonic Slicer to attack the low parts or the Spin Wheel to attack the high parts when you're above it. You don't actually have to destroy this guy at all if you don't want to bother with him. Especially the second time you visit this stage, when you'll want to go for the heart tank instead.
Instead of following the minboss, climb the right wall. You'll find a large health pickup here. Cling to the right wall under the entrance to the small room and dash jump to the left to grab on to the platform. Climb up here to get the Heart Tank. It might take a few tries. You might find this easier if you come back after beating the level and use the charged Bubble Spray. The shield it generates lets you jump higher underwater.
Down below, you'll meet a gross jellyfish.
These things slowly move around in the water, occasionally stopping to emit an electric field. Another enemy with low HP. Don't worry about them too much.
When you see a narrow hole, slide down the wall to find some health. Head back up and to the right. Stay low and you'll find a room with some weapon energy and more health. A bit farther along you'll see a health item underground.
The proper way to do this is with the Bubble Splash. Charge it up and jump straight up from here. When you reach the top of the water, you can actually sort of "double jump" out of it if you time it right and jump right from the surface. Make your way to the ledge with the sub tank and grab it. The sneaky tricky way involves taking advantage of a weird quirk of this game. You jump a little higher when walking down a slow. Walk down the slope on the left side of the ground and jump up and grab the wall below and to the left of the sub tank, then mash the jump button to jump along the top of the water to the right and up onto the platfrom. Weird!
Continue right. You can dash jump over this pit but there's a floating platform here if you need it. The second floating platform over another pit will let you reach the wall above, which you'll have to climb. Go right inside of the hole in the wall to continue the level or take a detour to the X-Hunter room.
Continue up past the hole in the wall and you'll eventually be end up inside. There's no item here to collect, so there's no reason to come here if there's no X-Hunter waiting for you.
Once you're inside, you'll meet up with some Scrivers and a new enemy.
These turret-like enemies crawl along surfaces and shoot lasers in three directions. They're not very strong, but they're often positioned in areas where you'll have to wall climb.
Climb the walls and platforms and make your way up past the Scrivers and Barite Lastars until you reach the boss' room.
I hope you're used to fighting underwater, because this room will be half or completely full of water, changing depending on Bubble Crab's mood.
The Hard Way
He's not too tough, even with just the X Buster. He'll jump around a lot with laser claws that will only hit you if you're directly above him. He'll sometimes erect a bubble as a shield that will absorb some attacks before breaking. He can shoot rings of bubbles at you, or release enemies in bubbles that will float to the top of the water. When the bubbles pop, the enemies will swim right at X. You can destroy them easily, though.
The Easy Way
Bubble Crab is weak to the Spin Wheel, which will pop his bubble barrier instantly. Try not to let him jump over it, since you can only fire one at a time and it takes a while to dissipate. Fire it close to him, or even under him when he jumps. You can also drop it on his head from above, since it always falls to the ground.
Your reward for beating him is the Bubble Splash, which shoots a flurry of bubbles out in front of X before floating up and popping. If you charge it, you'll gain a shield of bubbles that's not quite as effective as the one Bubble Crab was using. This shield will allow you to jump much higher underwater.
Go right back into Bubble Crab's stage and collect the heart and sub tanks if you couldn't get them without his weapon and the arm parts. Then head on to Flame Stag's stage.
NEXT: Flame Stag