>>9952788Short answer:
They are from 'Collectable Figure Sets' sold in the west back when the Digimon dub first aired.
Long answer:
-Devimon's mold is from the 1998 'The Digimon' figures which came in small plastic cages
-Metal Seadramon's mold is from a Digimon Pendulum line of keychains in the same style as 'The Digimon' cage figures
-Mugendramon's mold is from the heroclix-style Digimon Battle Figure game (pic related), which never made it outside of Japan
Most 'The Digimon' and Digimon Battle Figure molds were repurposed and packaged together in the west as a 'Collectable Figure Set' line. Which is what these three specific figures were from.
Notably, the western version of 'The Digimon' figures are all missing some of the painted details the Japanese versions had, and are made of much cheaper plastic. The repurposed Digimon Battle Figure molds are mostly identical in production to the originals - they are simply missing the base.