You have great type synergy here. I just had to giggle a bit when I read that everything on the team except Swampert resists Grass. If switching is your thing, you can switch almost whenever you want with this team with very limited consequence.
Regarding Quick Attack on Scizor to deal with Infernape, I really don't think that should be an issue. It's pretty easy to predict a fire attack in that match up, and if they know you have Heatran you can switch to Salamence for Intimidate and resistance on both STAB.
I'm a bit skeptical of that MixMence set, but if it works I can't really argue with that.
The biggest thing I'm noticing is your lack of variety in attack types. You mentioned that Rotom is a bit of a problem, and that's probably because you don't have a single Dark or Ghost type attack on this team. You've got Earth Power, Earthquakes, Fire Blasts, Heat Wave, Grass Knot, HP Grass, Ice Beam, HP Ice, U-Turn, X-Scissor plus Dragon for very little coverage. The only other attacks are Thunderbolt, Brick Break, and Bullet Punch.
This seems like a team that will simply just go full throttle and try to pull off a victory however it can, which makes me uncomfortable. However, I think that says more about my play style than it does the viability of your team. You have 6 individually powerful pokemon that cover each other's weaknesses well, but don't necessarily address all threats. The sheer power of these attacks does make up for this, though.