From my understanding of events, FNAF 2 is indeed a prequil. You can look up all the evidence later, but it can be gathered that FNAF 2 takes place in 1987 (before the original game). The only logical way to explain all the events in line with canon chronologically is as follows…
There are three restaurants. You heard me right, a grand total of THREE Fazbear Pizzeria’s. The original location, the location in second FNAF, and finally the location in the first FNAF.
On night one, it’s easy to assume that the phone guy is referring to the location in the first FNAF. It’s easy to make parallels with the “bad publicity” and the events described in the first game, but I believe them to be entirely separate issues.
The first location of Freddy Fazbear’s Pizzeria is home to the oldest set of animatronics, which are the withered versions we see in the second FNAF. Unlike the animatronics in the original game, their appearances did apparently scare children. My theory is that the original pizzeria had bad management, horrifying mascots, and just all-around bad publicity. It wasn’t actually haunted, it was just shitty and unpopular. This is why the phone guy tells you to, quote-on-quote, forget everything you might have heard about the old location.
It can be noted that Golden Freddy was an actual animatronic at the original location, as can be seen by the wires and machinery inside the GF suit in the second game. His purpose? No idea.
The second location is where the actual haunting begins. My understanding about the onset of the haunting and the marionettes involvement is still vague at best, but I’ll tell you what I do know. The second location is the actual start of the franchise as we understand it. There isn’t a need or want for more power, and the grand re-opening is off to a good start initially. There isn’t as much of a concern for employee safety, as there haven’t been any serious complaints yet - just concerns voiced by the original night-guard. Things at this location quickly go downhill when the events mentioned in the original game start to transpire. The bite of 87’ and the murder actually happen at this location, eventually leading to the restaurant’s shutdown.
The third location is the setting for the first FNAF. It’s not fancy, and there is a lot of financial strain due to the failures of the previous restaurants. The redesigned animatronics are scrapped, and the company decides to return to the more “realistic” appearances of the animatronics at the first (unhaunted) location. The newer additions to the Fazbear family are also removed (probably due to budget issues) meaning BB and the Marionette (though BITCHnette *excuse me* might have hitched a ride to the new location somehow). This brings rise to the third set of animatronics that we know from the first game. We do know for sure that whatever bad spirits that were pulling the strings at the second location were brought over to this location as well. Bummer. I think Fazbear entertainment is probably done for at this point, but who knows?
There is SOLID evidence that there are three individual sets of animatronics. To prove this point, I put a picture of the 3 different versions of Chica at the top there. You’d assume that the first image is from the first FNAF game, but it’s actually the Chica you see when you beat a night and are looking around the stage through Freddy’s eyes (yeah it’s different - notice how the one in the middle doesn’t have eyebrows and the jaw is lower). This means that this Chica design is also a CANON version of Chica in the second FNAF. Three Chica’s, thee Freddy’s, three Foxy’s, three Bonnie’s. Boom. Mind blown.
Also *cries* my Foxy headcanon is mostly dead, but do not fear. We have learned things here today.