This is the the playlist walkthrough as some people found it difficult to understand, I will mostly cover the key puzzles or perhaps the whole thing.

Level 1
Main Objective: Disable the Blue button
Solution: You need to kill all cats holding down the blue buttons in order to pass throughout the last sector, start from going down and try to get the pig to the first sector (on the water), MAKE SURE YOU KILL THE CAT FIRST.
Once you get the pig up, let your campinion join you to the left sector and then boost him towards the upper sector to kill the other cat.
try to get your friend to the right sector via the black button then the bridge, then as soon as he reaches the right sector, let him contact the explosion block next to the saw so you can access the right sector as well
Now go kill the last cat and finish the level.

Level 2
Main Objective: Get to the exit
Solution: First part is easy, just boost your friend upward and throw down the boat so he could join you later on.
Second part is easy as well, just throw your friend to the other side and then let him throw the rock towards the required place.
This part is difficult: One of you will have to jump towards the first gap, while the other one will have to act as a platform to allow another jump ability for the first player. Using the teleporter, the second player can act as a platform for the first character to be stepped on. Be quick!
Last part is easy as long as you do not destroy the explosion blocks.

Level 3:
Main Objective: Activate the red button
First thing is simple, throw your friend towards the monkey bars and let him press the orange button. (he will be experiencing some extreme parkour, be warned.) Once the rocks are lowered, follow up with your friend
Throw your friend to the red button blocks and then help me elevate to the top via the bridge block. He will then press the red button for you to pass.
This part is tricky, once a toast is burnt, contact it then quickly go towards the water.
This rock part is somewhat difficult. one of you will have to stand at the red button while the other moves the rock towards the catapult, as soon as the rock is lifted off, the player on the red button should grab it.
The exit will be at the teleporter back in the toast area.

Level 4:
Main Objective: Getting the Jetpack
This level strictly requires both players to remain alive, as they will be working together in separate areas.
Solution: step on the pink button and let your campinion touch the explosion block next to the laser, then quickly get back up and lift your friend to the upper sector.
Let your friend step on the sand button to levitate the elevator block for you, stand on it and do not jump off of it until the elevator block runs out of feul and begins to descend.
Continue moving to the left now that your friend openned a path to the left.
Now you are at the key part, The first thing you need to do is unblock the laser in the upper section, so take a head copter and get up there.
This requires the same trick as level 1, when your friend is on the bridge block, step off of it and quickly run towards the sand button on the left.
That's the cat down, your friend should stay on that sector now, don't worry, you'll get back to him.
Go down and get the puzzle block towards the pink button, now you don't need to worry about pink button blocks anymore. MAKE SURE YOU OPEN A PATH FOR YOUR FRIEND TO PASS VIA THE SAND BUTTON NEXT TO THE PUZZLE BLOCK.
get back to the first area and get to your friend.
The rest is honestly easy, just get the jetpack for you and your friend and go towards the teleporter top right. Then some simple coop and that's it.

Level 5:
Main Objective: White button
Solution: throw your friend towards the fan and let him turn it off, then stand on the button to lift your friend towards the next space, then follow up with his hand on the edge of the gap.
Get up into the upper sector, on your left is the exit, blocked by a fan, it needs to be disabled via a white button, and on your right requires you to throw your friend to the other side.
The maze is pretty easy to solve, just avoid the acid bubbles and move the puzzle block towards the left white button.
Throw your friend to the other side then step off the blue button so your friend can elevate himself without being thrown back to the right side.
both of you get on the boat, then go towards left, when you land, continue towards the forest part, it'll be easy from this part.

Level 6:
Main Objective: Blue Button
Solution: Get in the teleporter.
there's a cat with the fire ball weapon, make use of it by burning yourself, then fall to the left but bump your head to the fire block, that'll boost your descent.
take the boat with you and your friend and get to the right.
you and your friend will have to jump giving a boost for one another, so one of you jump first, then while one of you in in midair, let the other player jump to give the first one a re-jump ability. Then move the puzzle block on the spike block, and step on the blue button to help out your friend, he will hang on the monkey bar, then the puzzle block, then jump to other side.
Help one another up, then step on the blue button for your friend to pass, as soon as he does, step off of it so he wouldn't get rejected back, but instead be able to ascend. Once he does that, let him do it for you as well.
For the laser part, close the laser beam via the puzzle block, and stay on the blue button, let one of you (who isn't holding down the button) go and allow the laser beam to pass, that'll kill the cat, once that happens, close the laser beam again, move the puzzle block to the blue button, and get into the teleporter.
You're back to the second part, throw your buddy towards the rocks and let him help you out by hanging his hand on the edge.
Exit is straight to the left, unless you haven't openned the blue button, I suggest you throw your friend back to the teleporter.

Level 7:
Main Objective: Green Button
This needs teamwork, a lot of teamwork, so don't forget your friend behind.
Solution: boost your friend to the green button and let the duckshark throw you to the other side, now open a path for your friend to pass.
stay on the brown button as your friend will take the headcopter and fly above you, then take it yourself as soon as your friend reaches the upper perimeter.
Move the puzzle block to the green button and keep it there.
This is probably new for some people, you can dash (moving then pressing the "attack" button, usually the D key or X button on Xbox controllers).so let your friend run towards the conveyer, then dash towards him, that'll boost him away from the conveyer. (WARNING: THIS MIGHT BE BUGGY FOR WEAK ONLINE CONNECTIONS.)
The teleporter part requires the green button to be unpressed, go down with your friend and reomove that puzzle block.
Last part is simple, throw your friend to the other side, then let him stand on the bridge button so you can pass.

Level 8:
Main Objective: Collect all Gems
Solution: as you have learned in level 7, you can dash your friend through conveyers to overpass them, make use of it.
now jump on the first bridge pads, and get ready to quickly jump on the next one, once you are ready to jump one last time, let your friend rush towards the button, make sure you stand on the explosion block for a final support.
Now drop the boat to your friend and open a path for him.
Cat part is simple, the elevator will require you two to elevate at a certain height, then one of you should throw the other to the other side and let the bridge open.
Now this part is a bit crazy, you will need to throw your friend while the two of you are on the raccoon.

Level 9:
Main Objective: Kill the cat.
Solution: boost your friend to the top and let him help you, you should jump towards the fire block on the right for a height advantage.
this part is solo, just fall the do a double jump to get to the other side.
Throw your friend to the left sector and let him get in contact with the explosion block, that'll give you access.
throw your friend again, but mind the saw.
Freefalling in here, just get to the bottom section and move the puzzle block to the button.
Now get back up and kill that cat, then jump back to the spawn point area.
Last part can be done solo, though it'll be better if you two cooperated.

Boss 1:
Now this is crazy, you need to go back throughout the whole level just to reach the exit, make sure you'd take the angel wings for your return trip.

I won't be writing more level solutions, if you want the head so badly, go figure out the rest. Otherwise replay the coop campaign.

Syntax