I guess the general agreement is on Ghost type, then.. I agree, mostly. The only way I can see him using a ghost would be if it was a particularly goofy one. Haunter was a good example of what I mean (but he never actually "caught" it, so I discount it). He most certainly will not go for an intimidating ghost type, Dusklops, for example, would never happen.
I could see him getting a Steel type, no problem. I think a Mawile would fit him pretty well, at least in terms of "style". But if he gets one, it would probably be one from 6th gen. Steel/Fairy type?