I agree maintaining balance is important, but it isn't necessarily the mere addition of new types that makes or breaks the metagame and triple battles are far worse concerning this issue. There are other factors that affect the metagame such as abilities, stats, movesets, items or what not. New types could lead to more interesting ideas for pokemon, stories, legends, moves and such. Pokemon isn't just there for the metagame.NO. ABSOLUTELY NOT.
Adding new types creates more baggage in the type chart, and it gets exponentially harder to maintain game balance as you keep introducing new types.
If you like, I'll work on a type chart, some tweaks included, to see if balance can still be maintained even with the addition of these types, but if that doesn't work out, then I might scrap one or a few of these fake types.
Oh yeah, I forgot to mention that Zombie, Plastic and maybe Cloth, Speed and Nuclear could have potential to be their own types. Sorry!:sweatlol: