Godzilla vs. Gigan

The 12th entry in the long-running Godzilla series, also known as Godzilla on Monster Island. It is the final film to star Haruo Nakajima as the King of Monsters. Godzilla must once again battle his old foe King Ghidorah to save Tokyo, and this time he brought a friend!

The plot revolves around a young manga artist by the name of Gengo Kotaka, who gets hired as a concept artist for a new theme park featuring a to-scale tower in Godzilla's likeness. He and his friends soon find out that the men running the theme park are in fact (surprise!) aliens trying to conquer the world with kaiju! Again! These aliens are in fact giant cockroaches disguised as humans from some planet in Space Hunter Nebula-M. They plan on summoning & control a couple of monsters with "Action Signal Tapes". Our human heroes activate one of them by mistake, which brings the attention of Godzilla and his pal Angurius, who are just chillin' on Monster Island (in the only scene that actually takes place on Monster Island). They chat.

Angurius pays a friendly visit to Tokyo, gets shot at, and goes back to tell Godzilla what's up. The aliens summon King Ghidorah and a new monster, Gigan, who may prove to be Godzilla's deadliest foe yet. Godzilla and Angurius show up to confront the alien duo with the final battle taking place in the aforementioned theme park, where it turns out the Godzilla tower has a giant laser.

With its excessive use of stock footage and special effects failures, this is generally considered one of the worst and campiest Godzilla films. However, some fans find it entertaining, and Gigan went on to become an Ensemble Darkhorse.

Tropes used in Godzilla vs. Gigan include:

Action Girl: Tomoko Tomoe, the girlfriend of the protagonist Gengo Kotaka, is a black belt and gets to demonstrate these skills when rescuing her boyfriend and his friends from the disguised Nebulans.
Character Development: Aside Destroy All Monsters, Godzilla makes one where he's longer no long a selfish monster since Son of Godzilla. In the next film, he becomes friendly enough to fight alongside other monsters.
Continuity Nod: The Japan Defense Force recognizes King Ghidorah's roar when the alien kaiju first approach. Also, Godzilla goes after Ghidorah, the monster he's familiar with, first before directly fighting Gigan.
Bash Brothers: Godzilla and Angurius. Also King Ghidorah and Gigan.
Did You Just Punch Out Cthulhu?: Gigan is notably the first villain to make Godzilla bleed.
Friendship Moment: Seeing Godzilla in trouble, Anguirus rushes to his aid, and receives Gigan's chest saw in his face as a result.
Stock Footage: Tons of it.
Stock Music: The film's soundtrack is almost entirely recycled music from other films, all of which were scored by Akira Ifukube. This actually works out to the film's benefit, as the music is easily the best part of the film.
Suddenly Voiced: Oh wow. Wasn't kidding about "They chat".
Weaponized Landmark: The Godzilla Tower turns out to be one