Nothing of any difficulty here. And if you find jumping onto the tower difficult, then I don't know how you managed to get this far...
This is your next big battle with Trouble Bruin, who has brought along his Flying Scythe. This machine is capable of shooting out an object that chops off a whole chunk of the tower. You can see when he's going to do this because he nods his head from side to side. When he does, make sure you're on the highest step possible. In fact, through the whole level, it's best to always aim to be on the highest step. Trouble Bruin's second attack involves closing his eyes and flying into you. If you're as high as possible, then he'll miss you, and you can hit him now by jumping and shooting downwards (be careful not to jump down accidentally). As you hit him each time, his rams will become faster, so you have to go as fast as you can to get to the highest step. He will choose his method of attack completely at random, meaning that you could be waiting a while for a chance to hit him, or you'll get enough chances in a row to defeat him quickly. Once he is defeated, the camera will stop moving, and you'll have to go to the top of the screen to enter the next level.
One final note: be careful not to fall!
As soon as you begin, Balloon Kelly will appear on either side of you, so go up the tower as fast as you can (go round and grab Hangman) to get him out of sight before he pops and flies into you. Next up, you'll see flamethrowers above, plus one beside the next Hangman, so wait until that one has stopped shooting fire until you go up (you can see when it is about to start firing). Now two balls will appear from the central pole, which you'll have to hit five times each to destroy. Their first attack involves rising to the ceiling and smashing the ground several times while circling, so watch out for that. Next, they'll spin around from the middle, and you'll have to time your jumps to avoid them. Then, they'll stop. One will rise, the other will descend, and then they'll spin round and round again, this time very quickly. After this, they'll start again.
Once they're beaten, keep going up. While you do, cannon balls will be fired, so just keep moving and they'll never hit you. Next up is Armordillo [sic], a soldier in a lethal ball, who'll enter rolling around the platform (you, meanwhile, won't be able to go round). Jump over him when he comes round the front, but don't stand right in the middle, because that is where he will suddenly stop, and open up. When he begins hopping to the left (make sure you're on the right), you'll be able to hit him underneath, but be quick. A great way to do this is to grab the Ticker Head when he is high enough in the air so you can hit him like crazy. But make sure you're out of the way when the head is cancelled, otherwise he'll land on you. After his second roll, he begins shooting his arm out at you when he reaches one end of the platform, so jump over it - don't worry, the red chain can't hurt you. Anyway, once he's finally beaten, the rest of the level is safe, so make your way to the top, and don't forget to grab the jellybean at the end - you're likely to have lost at least a bit of health after the last two scenes.
Spinderella will rise out of the ground, spinning around, and Beau will reveal the target - an enormous power supply at the back of her body. Meanwhile get yourself standing not too far from one of the spikes (you'll see why in a moment). When Spinderella stops, she'll start throwing her arms at you. To dodge them, simply run away from wherever each arm is coming from - i.e. arm from the left (NOT her left), run to the right. Arm on the right, run to the left. Soon, she'll keep her hands on the ground, so when the last arm comes down, don't stop running because you now have a chance to sneak round the back and cause some damage to her power supply. Standing next to the spike earlier on ensured that you wouldn't end up with a spike in your way when you went to hit the weak point.
Now she'll repeat all of the above again, and then, the third time round, she won't throw her arms, but grab the platform and spin it around until you're on the other side. While at the back, you won't be able to see the power supply when you go to hit it, but you'll know when you're under it because her arms will be right in the centre of the screen. She'll repeat her 'thrashing arms' sequence two more times. and then spin the platform back round and start all over again.
I'd advise remembering the sequence for this boss, otherwise you may find yourself very overwhelmed.