Rarely found in the wild, these bizarre Pokémon have not only different appearances, but different types from their normal selves. They act similarly to shiny Pokémon, with each species of Pokemon having a different appearance and typing from their normal selves.
Understandable, but no, they're different in function. These Deltas are like shinies and have a chance to appear for every encounter. Plus there's one for every single Pokemon. Arguably, they're a lot more like the TCG Deltas than Insurgence's.
I'll admit though, Naukan Forms are probably more similar to Insurgence Deltas, but a lot of them have different stat distributions, a bit more like Alola forms.