If I remember correctly, he says it after they return from the past and before Shindo's nuclear submarine is attacked by Godzilla.

He doesn't. No one does.

My mistake. After watching it again, the scene in question is at 58:27. Terasawa finds a newspaper article referring to the disappearance of a nuclear sub in the Bering Sea. However, no date is actually stated nor is a date visible on the paper apparently. It can only be presumed that the sub must have sank sometime before 1984.

Alright, I think I'll take a crack at this, but in the original manner intended (according to my own personal opinion):

The question was the number of Godzilla specimens seen throughout the franchise. I'm gonna try and use the "Godzillas per continuity method", whereby I count the individual Godzilla specimens in each separate continuity (films only). Here we go:

Showa: Two Godzillas, the original and the next main one, and one infant (Minilla)

Heisei: Two Godzillas again, the original and another unmutated one that was mutated inot a second, and one infant turned adult (Godzilla Junior)

2000: Unknown, either one or two Godzillas (could be the original survived, or this is a second one)

VS Megaguirus: One, the original who survived

GMK: One, the original who returned from the dead

Kiryu Saga: Two, the original and a second

FW: Unknown, either one or two (the original survived, or this is a second one), and an infant, Minilla

Legendary: One, the only one known in the series so far

So, how many Godzillas in total is that so far? Well, if we discount the ones where it's technically just the original, count infants, and allow iffys to be second Godzillas, then we have a grand total of: 10 separate and unique Godzilla specimens.

You're not counting the second [Heisei] Godzilla unintentionally created by the Futurians. I'm guessing this is because the second Heisei Godzilla born from a Godzillasaurus is actually the original? But... what about Destoroyah? He was born from the Oxygen Destroyer which was used to kill the original Godzilla, but the original Godzilla was erased from existence and turned into Godzilla 1991 so they are the same but they can't be the same so........... or did the Godzillasaurus turn into the 1984 Godzilla? That's not mentioned to be the case... ...... I think it's easier if we count both Heisei Godzillas (1984-1989 / 1991-1995) as different.

My theory has always been this: the Godzilla that attacked in 1954 was a separate creature from the Godzillsaurus on Lagos Island. It still attacked Tokyo in 1954 and was killed by the Oxygen Destroyer. The other Godzilla was created when it was exposed to radiation in the Bering Sea and it went on to attack Japan in 1984 and 1989. In 1991, it was weakened from being infected with ANEB and fed off a massive nuclear submarine sent to create Godzilla since the humans were unaware he already existed. The huge amounts of radiation Godzilla absorbed from the sub allowed him to grow to 100 meters and overcome the effects of the ANEB. This is the only way to explain how the events of Godzilla (1954), The Return of Godzilla, and Godzilla vs. Biollante can all still be referenced even after the timeline was supposedly altered.

So the Godzillasaurus that the Futurians "erased" still became Godzilla 1984 and then the nuclear submarine didn't mutate him into Godzilla, but just made him a little taller and stronger? And Godzilla 1954 was a different Godzilla. But what about King Ghidorah? He attacked Japan in 1954 instead of Godzilla... unless they both attacked Japan...

The appearance of King Ghidorah still doesn't make much sense. They never say that he attacked in 1954, only that he suddenly appeared in Japan. They still refer to the first Godzilla's attack in 1954 in Godzilla vs. Destoroyah, so that Godzilla must have not been the same creature that the Futurians moved. I'm assuming that due to the flow of time (or whatever) King Ghidorah suddenly materialized in 1991 (or 1992 because I think the movie actually takes place in 1992).

Yeah, it's all a little foggy, but this is really the only way to explain how the original still exists in history, AND how there's still this Godzilla running about in the Heisei. They just THINK they erased him from their history, because, well, Godzilla is Godzilla. They never truly changed the past, because they had already experienced what happened when they did.

I Will Make A Complete List Of The Many Godzillas.

1.Godzilla 1954

2.Godzilla(Showa)

3.Godzilla(Heisei)

4.Godzilla(2000 Millenium)

5.Godzilla(Vs Megaguirus)

6.Godzilla(GMK)

7.Godzilla(Kiryu Saga)

8.Godzilla(Final Wars)

9.Godzilla(Legendary Pictures)

10.Godzilla(Hanna Barbera)

11.Godzilla(Marvel)

12.Godzilla(IDW)

13.Godzilla(Dark Horse)

14.Godzilla(Atari)

15.Godzilla(2016)/Shin Goji

16.Godzilla(Tristar Remake)/Zilla

17.Godzilla(Godzilla:The Series)/Zilla Jr

18.Godzilla(Snickers Commercial)

19.Godzilla(HeritageGoji)

20.Godzilla(Godzilla Vs Charles Barkley)