First beat the elite 4 3 or 4 times then you see him in profesor oaks office
Where Did Red Go After You Beat Him On Mt.silver In Pokemon Heart Gold?
After you beat the elite 4 again he comes back 4 a rematch
He leaves but comes back when you beat the ELITE 4.
First you beat the elite 4 3 times then red comes back and leveled up his pokemon by 10 levels
Incorrect. There is no Elite 4 in Kanto (in HeartGold). So the Theory that you beat the Elite 4 then you can rematch is incorrect. I don't know how to battle Red (Ash) again, but I do know that there is no Elite 4 in Kanto (in HeartGold).
He goes to the bathroom
I don't know where he (Red) goes but I will try the answers but I'm pretty sure he didn't get a bite from zombies.
He died from getting bite by zombies