You have to time your jumps between the moving rats, quickly going from pipe to pipe.
You have to make a series of three jumps between the rats to reach the red wheel at the upper right (to dump the sludge on Ratman). Then evade the flies and jump from the big raised pipe over to cuff Ratman.
Defeating him has nothing to do with milk. There is no milk to be found anywhere on Super Power island.
You have to make a series of three jumps between the rats to reach the red wheel at the upper right (to dump the sludge on Ratman). Then evade the flies and jump from the middle raised pipe over to cuff Ratman.
Turn the red wheel on top of the last ledge.
When you face ratman and his rats and flies, climb to the red wheel at the upper right, which will dump sludge on Ratman. Jump quickly between the rats. Then avoid his flies to jump over to him and cuff him.
Ratman is hiding in the sewer under City Park, with his pet rats and stinging flies.
Ratman is on Super Power Island. There is a large rat in the sewer entrance to the factory on 24 Carrot Island (climb up into the bypass pipe to elude him).
You can beat the 5 non-flying villains in any order. If you are working left to right, the next is Ratman in the sewer under the restrooms.
You can defeat the 5 villains in any order. Copycat and Speeding Spike are Downtown, so the next villains are Sir Rebral in City Park and Ratman in the sewer under the restrooms.
You have to get the flies away from Ratman to defeat him. Climb up past the three rats on the right side to reach the final red wheel. Click it to dump sludge on Ratman. Now the flies attack you, but you can dodge them long enough to jump to the large center pipe, and over to where Ratman is.
It is not extremely difficult after some practice. The hardest parts, even when you know what to do, are the battles against Ratman's rats and against Crusher. (see related question)
The pay phone will ring when you have defeated the first 5 super villains (Copycat, Speeding Spike, Sir Rebral, Ratman, and Crusher). Answer the phone and you get the power to fly! Then you can defeat Betty Jetty.
As you defeat each villain and handcuff them, you return to the prison, then go right to the city again. When you have defeat all 5 of the super villains (everyone but Betty Jetty) the pay phone will ring on Main Street and you will receive your super flying power. Then you can go to the skyscraper Downtown and fly up to chase betty Jetty.