Godzilla and Gamera finally arrived at the nearest whirlpool exit
Gamera: i gotta say, i'm a little nervous to know what's it like up there
Godzilla: don't worry, i'll show you around and explain the rules. let's go, Infant Island is where were heading.
and so the King and the Defender, used the whirlpool to exit the Hollow Earth, unbeknownst to them however, the queen Gyaos was following them. Hellbent on revenge.
Hours later, Godzilla and Gamera arrived on Infant Island, there on the Island was Mothra and Battra.
Mothra: Goji!
Godzilla: *smiles* Mosu
the King and Queen nuzzled eachother reunited again.
Mothra: how's your arm?
Godzilla: *shows his fully regenerated arm* just fine now, Mothra
Mothra smiles, while Battra was distracted by Gamera.
Battra: hey, Godzilla, who is this?
Godzilla: i'm glad you asked, Battra, this is Gamera The Protector of Peace.
Gamera: nice to meet y'all. Looking forward to being with you all and learning the ropes.
Godzilla let out his alpha roar, summoning all the other Titans too him to announce the King's return.
Then what follows is basically the post credit scene in Zilla: New Arrivals
BINABASA MO ANG
Gamera: The Hollow Earth
ActionDuring the events of Zilla: New Arrivals, deep below the ground in the Hollow Earth, Godzilla is trapped by an army of deadly creatures, that is when he is helped by an unlikely hero: Gamera, Defender of Peace