What the... ok, the first noticable thing is dear god that is OP beyond belief: preventing abilities from working AND losing HP is too OP for me because I hate Trick/Switcheroo. +, that will make Gastro Acid lose its value a bit and will make Regigigas and Slaking viable in OU/Ubers, making Slaking and Regigigas double as powerful, as Slakings ability halfs the total turns it can "move" and Regigigas will have abnormal stats otherwise. I have a conclusion of NEGATIVE. Also, its fling damage is WAY too high, just give it to a fast Dark-type and take advantage of the fact it doesnt lower speed.
Also, I have 2 things to say:
1.@Namine, good job for saying what it might be used for, and I would like to suggest anyone proposing should name its uses to the metagame, if none, importance to the game itself.
2.I would like to propose an item:
Color Cylinder
Changes the type of Porygon line to a random type, an auto Conversion-3 (gonna propose that later)