I, too, would be interested in a fix to the Heatran code. I found one elsewhere that worked, but only worked once, and I can't figure out why. This is the other code I found. It was advertised to work in any Diamond, Pearl, or Platinum, but I've only tried it in Pt so far.
Heatran rebattle possible alt:
94000130 FCFF0000
B21C4D28 00000000
B0000004 00000000
20001144 00000001
20001287 00000017
D2000000 00000000
Any help would be greatly appreciated!