Man. I just had the worst day ever. And to cap it all off, 8 hours of Comp. Org. work made me miss out on getting in my opinion at the very beginning of this thread (cause you know, it is not nearly as fun to rage when most people agree with you). But I will not let that take away my fun. So time to bring hell down on Multitype.
First, I will start off by saying that Multitype adds nothing to help CAP2 fufil its concept. Sure, it is cool, and it would certainly add more versatility to the Pokemon, but the point is, we are here to study Sketch. Multitype does not help with that at all.
Secondly, Multitype distracts from our goal. One thing I have said repeatedly over on IRC is how CAP is similar to a science experiment. In this particular experiment, the independent variable would be sketch, and thus our goal is to see how the dependent variable (the metagame) is effected by the introduction of a Pokemon with the independent variable. Multitype has such a huge effect on a Pokemon, that it is almost the equivalent of Sketch in terms of the magnitude of the variable it brings into play. While I'm sure many people here can already see what I am getting at, the point is that an experiment with 2 independent variables will inevitably fail because even if results are witnessed, it is impossible to tell if the results were caused by variable 1, variable 2, or the combination of both.
An important third point is that choosing Multitype really takes away from the CAP process. It decides multiple polls at once and in my opinion is just not good for our process. To be honest, I really just don't see a place in CAP for Multitype at all. Maybe if the concept was specifically focused on it, but in general, all it does is hurt our system.
Finally, I would like to mention something I consider a very important balancing issue that is almost completely overlooked on Multitype. Multitype would render the Pokemon immune to ability eliminating or stealing effects, and, as long as it is holding a plate, grants it an immunity to Trick, Knock Off, and other similar moves. When it comes to a Pokemon who already may be be a major threat due to its unpredictability, giving it that many more chances to get free turns of set up is just asking for it to be made broken. While this is certainly not the most important factor in my opinion, it is definitely an important and ofter overlooked feature that Multitype brings to the table, and as far as I am concerned may be reason enough in this situation to not give CAP2 Multitype.
And of course all these reasons don't even touch on my personal feelings about the blasphemy that would be giving it Multitype. However, in this case, the competitive reasons should be overwhelming enough for us to realize how bad of an idea Multitype is.