Once you have defeated him in battle there is no other way to fight him again unless you saved before the fight with heatran.
What do you do after you battle heatran?
Simple you cannot find him if you caught him then either in your PC box Or party if you maid him faint then you may NOT battle him again
When you reached your 21st battle you will battle Palmer and his Pokemon are: Dragonite, Rhyperior, and Milotic When you reached your 49th battle you will battle him again and his Pokemon are: Heatran, Regigigas, and Cresselia
I believe you can't find him anymore after battling Heatran.
battle with her (heatran's a girl) or trade it or use it in a contest.
simple if you did this you would not be able to aquire heatran ever again unless you restarted the game all over again
In battle tower multi battle room salon.
You Need Action Replay DS/DSI for this one Re-battle Heatran Code: 94000130 FCFF0000 B21C4D28 00000000 B0000004 00000000 20001144 00000000 20001287 0000000C D2000000 00000000 Oh, You Need Master Balls too 999 Master Balls: 94000130 fcff0000 b21c4d28 00000000 b0000004 00000000 000000f5c 03e70001 d2000000 00000000 How To ReBattle Heatran 1.Press L R with The Code while the game is on 2.It is same as 3 lake Pokemon codes, but When you do the cheat in front of Heatran's room, Buck appears and take Magma stone again and he returns home, then go to his home so he goes to put it back. Now there is Heatran again. 3. So You Must Press L R in FRONT OF HEATRAN'S ROOM
to get a heatran, you have to of been to the battle grounds (bucks grandpa owns it) in the survival area then you go to the strak mountain and then you travel through it with buck until you get to heatrans cavern, then you find him and will have to battle him.
Go through Stark Mountain with Buck. After you get out, go back in and go to the place where you met Charon again. Heatran will be there.
You can find her in the Battle Tower multi battle room
heatran just beat Cynthia again and he will be capturable now if you do capture heatran .well fill up your national pokedex