That said, there's a lot of ground to cover in the single player campaign. We already provided some general tips on how to get through Octo Valley, but along the way, you'll run into some big bosses that require strategy to defeat.
Here's a breakdown of the five enemies you'll go up against, and how you can soundly defeat these guys.
The Mighty Octostomp
This big, square creature is a large, hulking nightmare that is not afraid to charge forward and crush you using his face. Fortunately he has a vulnerable spot that's easy to access.
When you first face off against Octostomp, cover the ground in as much of your paint as you can. As he charges, get into squid mode and immediately swim out of the way. While he's face down, you can shoot at the panels on his sides and work your way up to the tentacle on his back, using your squid swimming ability. Once you're up there, shoot away and he'll transform into a smaller yet tougher Octostomp.
There's a twist with each of his phases. Not only does he get a little faster with each turn (and more accurate with his charge), but his side panels change, first in a diagonal pattern and then with moving panels. The strategy, however, remains the same. Avoid his charge (using the shoot and swim technique), then shoot paint on his sides, work your way up to the top, and take out his tentacle before he has a chance to flip back over.
Follow this procedure and he'll be defeated, leaving a Zapfish and Sunken Scroll for the taking.
The Dreaded Octonozzle
Think of this creature as a glob-covered kitchen sink with eyes, ready to strike with every ounce of evil ink he can muster. Thankfully, he can be defeated.
The first thing you'll notice is the bright suction cup spots on the Octonozzle's neckline. You'll want to begin shooting at this immediately, while avoiding the shots he takes from his cannons (usually by jumping over them or swimming out of the way in squid mode – just make sure you shoot ink on the ground first). Once you hit this spot, you can shoot the side of his head, swim up, and blast away at its vulnerable spot, a tentacle.
This procedure will work two more times to eventually defeat him, but you'll need to watch out, as his rate of attacks increase with more cannon fire, and more suction cups to shoot at. Remember to keep firing at these weak spots, and avoid having an abundance of his ink covering the ground in front of you. Once he's wide open, shoot the side of his head, get to the tentacle, and fire away.
Eventually, he'll turn into an ink explosion, and the captive Zapfish will be yours.
The Rampaging Octowhirl
While the Octowhirl doesn't have the size of the last two bosses, it does have the speed, and this can pose a big problem for you.
It has two general attacks. The first is a water sprinkler-like attack that sprays ink in all directions. Try to avoid this spray at all costs, as it can cause you harm and force you to stay above ground. The second attack, however, is a charge attack, which you'll see coming.
The strategy is simple. You'll want to shoot ink all around your area before the Octowhirl can charge you. Not only does this give you room to reload and swim around, but it'll get stuck in this ink once it's in contact with it, revealing its tentacle. Shoot away at it, and it'll get a little faster with each new turn.
Repeat this strategy for the next two turns – dodging its sprinkler technique and shooting when it's vulnerable – and the Whirl's world will stop spinning.
The Ravenous Octomaw
The Octomaw poses one of the biggest boss challenges in the game, a huge, hulking beast that will make no reservations about eating you.
It will first dip into its own ink and try to pop up to eat you. The goal here is to watch out for its fins so you don't get injured when it pops up. From there, you'll see that its teeth surround you. You'll want to find an opening by shooting away at one particular tooth, then swim out of there.
Once you do, the Octomaw will appear again, showing the opening you left. Destroy the remaining teeth (it may take more than one turn) and then hurl a grenade in there (preferably a Burst Bomb or Splat Bomb) and you'll stun it long enough to reveal the tentacle on its tail. Run around quickly and shoot at the tail, and it'll go into its next phase.
These attacks remain the same for all three phases, but the teeth will get tougher with each go-around, turning to silver and then gold. However, just keep shooting and finding the vulnerable spot to hurl your bomb, and you'll finish it in no time, resulting in another Zapfish.
Finally, there's the leader behind the whole alien attack, who refers to himself as The Octobot King, or DJ Octavi0, since he houses a weapon-laden deejay station. His boss fight is the longest in the game, but he can be easily defeated.
First off, you'll want to watch out for his homing missiles. He fires two in one shot quite consistently, but you can easily blast them with your rifle. From there, watch out for his large robotic hands. He'll hurl these your way as he attempts to pound you into the ground. Your job is to shoot one of these hands, so that it'll fling back and punch him backwards, further into the stage. Once you catch up with him, he'll fire a large, charged missile at you. Shoot at this like crazy, and it'll eventually reverse its flying direction, hitting him instead. This concludes the first stage of the battle.
Next up, DJ Octavi0 repeats the process of the first stage, but throws a large ink laser into the mix. You'll see him charge up for his attack, so get out of the way of the laser and continue to shoot at his missiles and fists. You'll knock him back again and use fan-based platforms to reach him, and he'll initiate the large missile attack once more. Shoot it, and you'll move on to the third phase.
Missiles and fist attacks will now speed up even more, so you'll want to make sure you have a steady supply of ink around, so you don't get overwhelmed. Look out for balloons that can cover the ground in a large amount of said ink, so you can swim around quickly and reload. Octavi0 will also shoot out spheres that spawn enemies, so take them out quickly, as you have enough enemy fire to deal with from the King. Wait for a good opportunity to shoot his fist, knock him back, take out the giant missile, and move onto the next phase.
Finally, you'll get to the final phase, with more attacks coming in, including minions, missiles and fists. You'll want to create an even larger pool of ink to keep safe here, since there's less room to work with. Try to stay on the sides, as the laser Octavi0 fires will aim right down the middle.
Again, watch for his fist attacks and hit them before they hit the ground, then deliver the final blow when he charges one more missile at you. Victory is yours!
Check out the video breakdown of boss battles from NintenU as well.