Hey, nice team. I've got a few suggestions for you.
Roar is somewhat redundant on an offensive Heatran. Your Heatran is an offensive variant, and woul much prefer additional coverage over a support move. Besides, Snorlax is a great phazer, and you really don't need Heatran doing it as well. I suggest replacing Roar with Earth Power, which lets you hit opposing Heatran, which can pretty much switch in for free, otherwise.
On Gengar, Hypnosis really isn't needed. Its accuracy is terrible, and Amoonguss has a 100% accurate sleep move anyway, so it isn't needed. I think replacing it with Disable would really benefit you. Most Pokemon only carry one attack to hit Gengar with, and it can take advantage of that with Disable, and get a Substitute up. It also shuts down Choiced attackers, too. Try it out, you'll notice a difference. It also helps you destroy Gliscor, which walls TyraniBoah without Ice Beam, so that's a plus too.
Amoonguss is cool, but I think that if you want to use it to its best effect in OU, you should try out this Double Powder set:
Amoonguss @ Leftovers
252 HP / 40 Def / 216 SpD
Nature: Calm
~ Spore
~ Stun Spore
~ Giga Drain
~ Hidden Power Ice
With two status moves, you can really screw over your opponent. Spore and Stun Spore will really destroy your opponent's momentum, even with things like Rotom-W / Scizor, which Amoonguss is supposed to mess up for you. With Specially Defensive EVs and its typing, Amoonguss can easily switch in on bulky Water-types, and then start doing its job. It can even live hits from things like Starmie. Hidden Power Ice hits other Grass-types, as well as Gliscor.
Good luck with the team, I hope I helped!