A Fusion Summon of this card can only be done with the above Fusion Materials.— The first sentence in the written text of a Fusion Monster with strict Fusion Summoning conditions.
A Fusion Monster with strict Fusion Summon requirements can only be Fusion Summoned using the Fusion Materials listed on that Fusion Monster Card. This means it cannot be Fusion Summoned by a card effect that does not use Fusion Materials (such as "Instant Fusion") or by using a Fusion Substitute Monster in place of a correct Fusion Material.
A monster whose name is treated as that of a listed Fusion Material (such as by the effect of "Fusion Tag" or "Elemental HERO Prisma") is considered the correct Fusion Material, so can be used for a strict Fusion Summon.
This condition is independent of being a Nomi or Special Summon-only monster; Fusion Monsters can have one or both of these conditions. Unless otherwise specified, Fusion Monsters with strict Fusion Summon requirements can still be Special Summoned by other ways that are not treated as Fusion Summons.