I have both games pre-ordered, but I'm not going to go out of my way to avoid spoilery stuff. Pokemon's done a pretty good job of keeping the things that I consider to be important and anticipation-worthy underwraps, but we can do your suggestion if others so desire.


[hider=Here there be spoilers]
The Pokemon Reboot theory I linked a while ago actually explores that a little. According to the guy who made the theory, Type: Null (and by extension, Silvally) is based off the alchemic chimera; a living creature made from multiple pre-existing creatures. The classic example is the Greek Chimera, being a combination of a lion, goat, and snake. In his theory, he suggests that Type: Null is the alchemic combination of the Alolan starters and that new Normal type dog pokemon in an attempt to create and control Arceus's powers. This would be supported by Silvally's ability and signature attack (RKS System and Multi-Attack).
[/hider]