Yet another pokemon with so few reliable counters. Jalorda has above average speed and bulky enough that it's not easily revenge killed by most scarfers. What can counter this apart from heatran?
Scarfed Shandera can kill non-Scarfed Jaroda (but then again, what doesn't Shandera kill) with Fire Blast. It also survives a +2 Leaf Storm, even if Rocks are up. This means that it can also kill Scarfed Jaroda as long as it doesn't have +4 Special Attack.
Scarfed Ditto can also kill all non-Scarfed Jaroda and have a 50% chance to kill Scarfed Jaroda. Personally, I like Focus Sash Ditto in Dream World as it allows you to sweep once priority and weather is gone.
Heatran doesn't necessarily counter Jaroda. Most, if not all, Jaroda carry a Hidden Power of one of the following types: Ice, Fire, Ground.
Ice hits the Dragon- and Flying- type pokemon for SE damage, which makes it the more popular decision. Dragonite is hit for ridiculously hard damage if it switches into a Leaf Storm then is hit by HP Ice, and random stuff like Zapdos and Xatu take more damage.
Fire hit the Steel-types, most notably Nattorei, who could otherwise wall Jaroda all day, since Glare helps its Gyro Ball, Leaf Storm does lol damage, and Leech Seed doesn't affect it.
Hidden Power Ground is what makes Heatran cry. Grass/Ground doesn't give much coverage, but it can lure in Heatran, Shandera, and Blaziken, all of whom die to a surprise Hidden Power.
I think that Jaroda is a very hard pokemon to counter if you don't know its set. Once you know its set, or more accurately the Hidden Power, you can counter it accordingly. Balloon Heatran is probably your best bet, though.