Hi. It's nice to see a refreshing TR team for a change. However, there are a couple of things that I think I could help you with.
Conkeldurr: I think that Payback can be replaced. Conkeldurr will practically always be moving first under TR, meaning that Paybck will only be hitting with a measly 50 BP. Facade hits bulky Psychic-types far harder anyway. I recommend switching Payback to Ice Punch, as this is your best shot at breaking through Gliscor, Landorus-T and Dragonite, who can all stomach a Facade thanks to massive Defense, Intimidate and Multiscale. Ice Punch will also hit Gengar for the OHKO, so Payback isn't really missed. Also, perhaps consider using Toxic Orb? It'll do less damage than Flame Orb in the first three turns, conveniently the three turns that Conkeldurr will spend under the effects of Trick Room.
Heatran: Heatran gets Eruption (with a fixed Quiet nature, 4th Gen event), which is an ideal move to use under Trick Room. With Overheat, you're forced to basically switch out after every STAB move, and thus completely wasting one of your precious Trick Room turns. Heatran can continue the flow of Eruption, while being powerful and very difficult to outspeed, not to mention bulky, and practically guarantee the win against a Sun team. So I'd use that over Overheat, and when you run low on health, consider Fire Blast/Flamethrower (preferably the former) over one of the coverage moves. HP Grass is your weakest, and bulky Water-types can easily fall to 2 Specs boosted Eruptions/Fire Blasts.
I see that you said that Donphan is your favourite Pokemon on the team, which makes me loathe to change it... But I don't really see what it does for your team. It lacks the massive offensive power than Trick Room sweepers need (since you have Leftovers) and since none of your Pokemon are actually Stealth Rock weak, Rapid Spin support is kind of wasted in my opinion. I think that you could use this slot for a Pokemon that can be fast and powerful when Trick Room isn't active (something that practically all TR teams need). Sciztar's idea of using Choice Scarf Salamence is a good one.
Good luck with the team!
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