It has been said that Pete Townshend coined the phrase "Power Pop" to describe the Who's sound in the early days.
If you listen to tracks like "I Can't Explain" and "So Sad About Us" I think that is accurate. You could certainly include some Beatles stuff in the genre as well.
In the 70's The Raspberries , Big Star, and Cheap Trick optimized the sound.
I know very little about the Monroes and had never heard this song until a few years ago. A nice mix of new wave and Power pop, it captures that feeling of being a lovesick teenager.
The Monroes "What Do all the People know"
The late Phil Seymour was Dwight Twilley's main collaborator in the Dwight Twilley Band.
He later went solo and released a couple of albums of good power pop in the early 80's'
20/20 were a late 70's early 80's power pop band who had minor success. They had a power pop magazine named after their song "Yellow Pills"
20/20 "Nuclear Boy"
I believe the Pezband were out of Chicago? They did some pretty good power pop in the late 70's
"Stop, Wait a minute"
The Pop were a band that didn't seem to get much exposure here on the East Coast (read: none!) I remember lead singer David Swanson having a solo album out in the late 80's that was more in the "Roots rock" genre.