The Wonderland Board

I noticed that in the first nine levels of world 4, a massive city far bigger than wondertown can be seen below. Is this Robot city? And where would it be located? Does anyone know?

Well, theoretically, it might not even be Wonderland. It could be another planet entirely, assuming the Z-Bots had space travel tech even before they were banished sometime between the Original and Adventures Trilogies.

How would it be possible for stinky and loof to travel there. A clue to support you theory is that the tenth level of world 4 takes place in space and features a lot of UFO's. In fact i believe that UFO's make their first series appearance in world 4.

Assuming RTW's Classic Level Set takes place prior to Secret Worlds, yeah, I believe that *would* be their first canonical appearance. As for how they would get there... I don't know; maybe the Rainbow Portals you go through at the end of each level magically know where the Rainbow Coins are and are capable of allowing for traversing between planets if needed in order to collect them?

Do you think that the robot city might have been on the Planet of The Zbots?

It's quite possible it was on Z-Botica. (I like to call it that because it being called merely the Planet of the Z-Bots even by them just seems a little bland to me. You'd think they'd at least name their home something.) There's no way to really know. Like I said before, this is all assuming they had the means for space travel before they were banished from Wonderland sometime between the two trilogies, which I think is more of a presumption, since we know they created the Sky Machine, which was in fact a spaceship (granted, it was programmed to crash on Z-Botica, as well as transmit the coordinates of Wonderland - which the Rainbow Stars presumably wiped from all of their memory banks and databases when they banished them - but I digress, it was still a spaceship, so it's entirely possible.)

First of all, in the deluxe pack of RTW (which i assume takes place chronology after the classic pack) we see that the Z-Bots have even more advanced technology than they had in the classic pack, when they kidnap Peggue and the other 3 come to rescue him. At the end of world 5 in the deluxe pack, we see some kind of teleportation device, which Stinky, Loof and Quookie use to teleport into space to rescue Peegue in world 6. We also see in the final level of world six that the Z-Bots have the giant motherships similar to the ones seen in POTZ that are seen when the Z-Bots are preparing to invade. I believe that sometime Between Return to Wonderland and Wonderland Secret Worlds, the elder stars banished the majority of the Z-Bots to the planet of the Z-Bots, only leaving some of the Class 001 Z-Bots and some of their motherships, some of which are seen in Wonderland Secret Worlds.

The question now becomes how the elder stars banished the majority of the Z-Bots. I have two theories. One is that the elder star simply forced the Z-Bots to leave on their own. The other is that the elder stars were some how able to teleport the Z-Bots to their planet. I find the later more likely, as it is unlikely the Z-Bots would leave Wonderland on their own will. They probably forced the Z-Bots to sign some sort of treaty that meant that as long as the Stinkers stayed away from the Z-Bots, the Z-Bots would remain on their own planet. By activating the Sky Machine, Morklin broke this treaty, causing the Z-Bots to attack. Seeing that the peace could not be kept, against the orders of the elder stars, Wysp went to the Planet of the Z-Bots.

You're forgetting something - the Sky Machine was designed to trick the Stinkers into giving the Z-Bots Wonderland's coordinates. It's implied that the "falling pieces of burning sky" were caused by the Sky Machine, being a secondary function - by using the Star Key, Morklin and the others stopped the meteors, but activated the primary function of the Sky Machine. There was never a treaty - the Z-Bots just didn't know where Wonderland was in comparison to their own location.