I'm definitely expecting following double types that would be sooo hyped
If they release one of those double types I'll have the Pokemon in my team immediately ^_^
About new added types I've seen not so many on fan site, always the same come back, it being Sound, Beast, Chaos, Cosmic,....
Well I have not that much inspiration but I keep in my heart this type from this Gen II Hack.... What was it? But the type was Crystal. Interesting set of weaknesses and resistances... Resists Electric, Rock, Ground but weak to water and fire, or something...
Another type I liked a lot was Blood type. Can't remember the set of weaknesses/resistances either but the owner of the idea was talking about associating all Normal claw-related moves to this type (Slash, Scratch, Fury swipes)...
And when I look to the type chart (which is very complicated and complete now, I must admit ^^), I can figure a bit that the following type would be funny and strategic to play :
Effective against/Water, Electric, Fire, Fighting
Not effective against/Ice, Grass, Psy, Rock, Dark
Resisted on/Fire, Fighting, Rock, Ground
Weakened on/Grass, Dark, Psy, Poison
Note that I don't have any idea how to name this nor justify these characteristics with logic, I just took all the types that in my mind lack something *insert confession bear pic here*
Nintendo always has a way to justify type weaknesses and resistances. But technically you can do whatever you want, that's really fun.