Latios gets the job done. It's not super over-powered like one would think; it's kind of like a rain team; has the potential to wreck anyone unprepared for it, but many good players prepare for it well, since really anything with a scarf and a SE move will force it out. Not to mention that it has to switch out every time it uses DM. That being said, it's a solid addition to the team; I sort of use him as my "filler" so to speak, since I can really just slap him on any team and have him do well (especially with HP Fire. It amazes me how few people expect it...)
Anyways, thanks for the suggestions; I'll add Mamoswine and Heatran ASAP, as soon as I can think of who to replace.