Must be Fusion Summoned using any 5 "Neos", "Neo Space", "Neo-Spacian", or "HERO" monsters, including at least 1 "Neos" or "Neo Space" monster, 1 "Neo-Spacian" monster, and 1 "HERO" monster, and cannot be Special Summoned by other ways.
Together with what Train said, we come to the conclusion that you need ONE OF EACH of the following.
1 "Neos" or "Neo Space" monster, such as monsters with "Neos" in their name, like "Elemental HERO Neos"
1 "Neo-Spacian" monster, such as "Neo-Spacian Grand Mole"
1 "HERO" monster, such as a monster with "HERO" in its name, as "Destiny HERO", "Vision HERO", "Evil HERO", "Masked HERO" or "Elemental HERO".
Clear enough?