Best Sun counter ever.
Heatran @ Air Balloon
Modest - Flash Fire
252 Sp. Atk, 252 Speed, 4 HP
At a glance, it seems like your typical offensive Heatran. Then one might notice the presence of Flame Charge. I know, WTF. Physical Flame Charge on a Heatran? Well, let's take a look here. What stops Heatran from brutally murdering the likes of Dugtrio and Sawsbuck? Its Speed? Well, fix that! Fire off a Flame Charge on a predicted switch, and he suddenly outspeeds just about everything that's commonly on a Sun team. Dugtrio can't KO him as long as his Balloon is intact, Sawsbuck finds itself outsped and OHKO'd by Fire Blast. Focus Sash Alakazam is a bit of a ***** with its Focus Blasts, but if it misses it dies. Venusaur, opposing Heatran, Arcanine, etc. can't touch him. Kingdra thinks he can beat him but finds itself 2HKO'd by Dragon Pulse and unable to OHKO with Surf thanks to sunlight. Offensive Lati@s find themselves 2HKO'd by Dragon Pulse, defensive variants are 3HKO'd, and can't do much in return. Metagross is OHKO'd by Fire Blast. Conkeldurr can OHKO Heatran after a Guts boost, but in turn Heatran OHKO's with Fire Blast. Skarmory can't touch Heatran, in fact, Heatran can set up on Skarmory without needing to fear anything.
Very little counters this monster, and almost everything that does
counter him is rarely if ever seen on a Sun team. Darmanitan can OHKO with Close Combat, but is outsped at +2. Slower variants or those lacking a Choice Scarf are outsped at +1. After a Flash Fire boost, he's OHKO'd by Sun boosted Fire Blast, or you can just shoot an Earth Power at him. Blissey takes 27-33% from Flame Charge. If you went with an Attack neutral nature, he'd be 3HKO'd, and you'd be at +3, ready to sweep your opponent's entire team. Chansey is a bit more of a problem, but you should still be able to beat it. Bulky waters wall it completely, but who the hell uses a bulky Water on a Sun team?