Genma Taisen

This is an often overlooked work of Rintaro and Katsuhiro Otomo. Otomo was the director of Akira, and many of the concepts and visual styles of Harmageon show up in Otomo's later works (including Akira). Harmagedon is considerd by many to be the building block of Otomo's later accomplishments. If you want to see where it all started with Otomo or with his style, Harmagedon and Akira are worth doing a comparison viewing. 

Both are Based on mangas by Shōtarō Ishinomori and feature a group of 9 heroes from different countries  

Both anime involve extreme battles between powerful psychic forces.