Learn French: Les danseurs préparant cette chorégraphie sont fatigués. - The dancers preparing this choreography are tired.

Yes! Using qui préparent (who are preparing) is actually more common in everyday spoken French. The present participle préparant is often used in writing to make sentences more concise, replacing the relative clause with a single word just like in English.

Why doesn't préparant have an -s at the end to agree with Les danseurs?

Because it is acting as a verb here, not an adjective. When a word ending in -ant (a present participle) has a direct object—like cette chorégraphie—it describes an action and is invariable, meaning its spelling never changes. It only adds agreement if it acts purely as an adjective (like in des mots blessants, meaning 'hurtful words').

Why does fatigués have an -s?

Fatigués is an adjective describing Les danseurs, which is masculine and plural. In French, adjectives must agree in gender and number with the noun they describe, even when they are connected by a state-of-being verb like sont.

How would I apply this lesson's topic to say the dancers are getting 'more and more' tired?

You would place de plus en plus (more and more) right before the adjective it modifies. The sentence would become: Les danseurs préparant cette chorégraphie sont de plus en plus fatigués.