These are the locations of the characters that appear in Nicktoons: When Toons Collide. Note: in every location are SIR Units since they function as warp portals. Chalkzone only can be entered through a school bord when obtained the Magic Chalk.
There are four zones on the map Suburbs, Forest, Downtown and Warp Locations. You first will be send to Retroville in the Suburbs.
Bikini Bottom lies underwater so you can just walk through Ocean Shore into Conch Streets and then to Kelp Forest and walk out of there to Pupununu Village. But to acess the underwaters you must have an air bubble.
The Wild Plains
Northern Water Tribe
Valley of Peace
Ba Sing Se
Southern Air Temple
Fire Nation Capital
Central Park Zoo
Topical Island is the starting location where the tutorial is. When completed this you will be send to Retroville but you can't return. Until you are ready to fight Nick you must go to Jimmy Neutron who will wap you there.
You will be warped to Nick's Kingdom from Tropical Island. From that moment Nick's Kingdom and Tropical Island are acesseble all the time.
The Juju World can only be acessed through the Juju Temple in the Pupununu Village by Jibolba.
The Ghostworld can only be acessed through Fenton Works or Master Mansion in Amity Park by entering the portal. When you go in it from Fenton Works you will arrive in Master Mansion and otherwise.
Can only be acessed after doing a certain mission with Cosmo who then eventually let you walk the Rainbow Path to Faiyworld from Dimmsdale.
Chalkzone can be entered through all schoolbords in every area, but you do must have the Magic Chalk that you get with a mission from Rudy to get it at Wayside.
You can acess this area in Human Town when you have completed a certain mission with Zim.
Pac-Land can be entered through the Arcade wich is located in Miracle City.