There may be many Pokemon Origins friends who still don’t know the guide to how to evolve HeartGold Gyarados in Pokemon Origins. Next, the editor of Sourcecode.com introduces the "Pokemon Origins HeartGold Gyarados Evolution Method Guide" for those who have questions in this regard. Friends, take a look below, maybe it can help you.
After Magikarp's level reaches level 40, he can evolve into Gyarados.
This method was derived from many experiments, so you can feel free to follow the guide. As long as you strictly follow each step, you will be able to solve this problem easily.