(Remember, these are just Ideas.)
It’s no secret that the bosses in the game are easier than the other waves themselves, and they all have the same patterns, despite the mission’s difficulty level.
The bosses should have more projectiles/higher Rate of fire/higher Projectile speed on higher difficulties. Maybe duplicates of the same boss on the same wave too?
Superchicken should have his Quad-Laser when you fight him individually. (“Is it a bird? Is it a plane?”) He should also fire more projectiles that go in random directions. (Like 30-50 bullets.)
The Space Crabs should have faster throwing and Lasers.
The U.C.Os should fire more eggs and lasers, perhaps faster projectiles will work too?
The CI4 Mother-Hen Ship should fire spreaded-out bullets, depending on how high the difficulty is. (Like 5 bullets on Difficulty Level 5.)
The Iron Chef could throw his ingredients at a faster rate, and fire his Charged attack 2-3 times.
The CI3 Mother-Hen Ship (Blast from the Past) could fire bullets at a faster rate.
The Veteran (Special Forces) should throw more grenades on higher difficulties (10 for Difficulty Level 6 for example.) He should also throw his knives randomly, instead of after the grenades.
The Party Chicken could fire his projectiles at a faster rate.
The Henterprise can fire the Giant Laser as they release Feathers, or when firing blue projectiles. Maybe increase the fire rate of the blue projectiles?
Darth Chicken should probably mess up the ship direction more often, maybe let him have more lasers? (7 on difficulty 8?)
The Yolk-Star should fire it’s lasers at a faster speed.
Chicken Multiplicity should have more Superchickens, or they split into more than 2 on higher difficulties.
(That’s all I can think of for now. Maybe some people will have different ideas for harder bosses?)
“More clones on “Show Em Who’s Boss” on higher difficulties, up to 8 clones at once.” - xdtruedame
“Egg Cannon needs more Health and the Eggs that are fired need to be Tougher.” - Thuongyc