Unlock the following characters by performing the corresponding tasks:

MONSTER - HOW TO UNLOCK
Bubba the Blob - Unlock the other 23 bonus monsters.
Eyegore the Alien - Beat the game with the "All Challenges Met" award for all cities.
Philbert the Ungulate - Beat the game with the "Par Scores Met" award for all cities.
Brian - Fully upgrade 12 monsters.
Fabio - Fully upgrade 3 monsters.
Sarah - Fully upgrade 6 monsters.
Squirmy - Fully upgrade 1 monster.
Vern - Fully upgrade 20 monsters.