the rainbow dragon the card it self has lots of effects its eff goes like this
Cannot be Normal Summoned or Set. Must be Special Summoned (from your hand) by having 7 "Crystal Beast" cards with different names on your field or in your Graveyard, and cannot be Special Summoned by other ways. This card cannot activate its effects the turn it is Special Summoned
this is some of the eff but the rest is proper
crestal best are light monmster remember use a type or atibute