There is a web of shows that have a hero machine, but these two share more in what they fight.
Both titles have large beasts that the hero mecha has to fight, that are more on the magical side.
In Golion it is more a team, in Koutetsu it is more a pair. But there was a combination sequence much like Golion(Voltron). Except the pilot in Koutetsu who actually transforms into the head.
I originally saw Koutetsu as (El Vegador) and Go Lion as Voltron, but the similarities are very much the same.