Small critique here, but I would use Hidden Power [Ice] over Dragon Pulse on Heatran. Below is the list of pokemon that resist Fire/ground (I think it's all of them):
Charizard, Gyarados, Aerodactyl, Moltres, Dragonite, Mantine, Ho-oh, Wingull, Pelipper, Altaria, Salamence, Rayquaza, Mantyke, Archen, Archeops, Ducklett, Swanna, Rotom W, Rotom H, Latias, Latios.
Now if we remove all the things that are very, very rarely going to be a threat to this team:
Gyarados, Aerodactyl, Moltres, Dragonite, Salamence, Archeops, Rotom W, Rotom H, Latias, Latios.
Of the list, you'll hit Dragonite, Salamence, Archeops, and Aerodactyl harder with HP Ice than with Dragon pulse. Additionally, the STAB on Fire Blast takes it's BP to 180. When hitting Gyarados and the Rotom forms, Fire Blast actually has the same resisted BP as Dragon Pulse. As far as the Lati twins go, here is your only draw back. You lose an effective 40 BP when attacking them, factoring in the extra 20 BP of Dragon Pulse and the Super Effective hit. However, the Lati twins aren't something Heatran really prefers to be up against, and can be played around with your team.
Trick Room is where it's at, you bitches. Trick Room all day, e'eryday.
Fuckin' up your sweepers since generation 4.