Here's how to defeat all the ghosts.

-Fatso near kitchen (Feed him hamburgers)
-Stinky (spray perfume on him)
-Stretch (use glue)
-Fatso in bathtub (use camera)
-General Fatso (use wind up key then hammer the tanks)
-Farmer Stinky (use hammer and chisel to carve the stone in Caspers Image)
-Graveyard Stretch (Use twister morph to lure him into grave dig site)