Greg does not go anywhere on Wimpy Wonderland. When you first see him, meet him at his house and he will be playing Video Games while you are out searching for Manny.
in kansas
his home. open the blinds.
You go to his house on Surrey St.
You have to go find Greg
win it
greg
you go into greg's room and on his dresser is the address book
Go back to Greg's house and open the blinds.
go to Greg's house then mum comes then Greg gives you the medallion.
wimpy wonderland bonus quest
He is either on Wimpy Wonderland or Wimpy Boardwalk. Hope that helped.
If you looked around you will find him in his house