Gamera: Super Monster (1980)

The final entry in the Shōwa era incorporates a ton of existing footage from the previous films and intercuts it with newly filmed footage, all the while pretending that the bouts Gamera is having with the half a dozen kaijū (Barugon, Guiron, Gyaos, Jiger, Viras and Zigra) are current. It compensates for the shameful act by having a crazy story about a young boy who befriends a trio of upstanding ladies that own a magic van and henshin into costumed space-women. The women even have a decent role to play in the madness.
The two uses of anime footage are from Space Battleship Yamato and Galaxy Express 999, respectively, but I've no idea why they're even there.

2 costume altering ear-pulls out of 5