Can you play without the crystal beast cards?

While the "Crystal Beast" archetype is designed to work together and benefits from having multiple different cards in play, it is possible to play without them. One can take advantage of Rainbow Dragon as a boss monster without the need of the field spells or other Crystal Beasts. Rainbow Dragon is summoned easily once 7 monsters have been sent to the graveyard in 1 turn (a common occurrence in master duel meta decks) and can destroy cards when it gains ATK equal to those monsters.

There is also a different Crystal Beast archetype that uses rank 4 monsters and XYZ that do not require the regular Crystal Beasts.