Learn Spanish (Latin America): Ese ballet tiene un elenco grande.

The position of grande changes its meaning! When placed after the noun (elenco grande), it refers to physical size or quantity, meaning a large cast. If you put it before the noun, it shortens to gran and refers to quality, so un gran elenco would mean a great or excellent cast.

Does grande always change to gran before a noun, even feminine ones?

Yes! Unlike some adjectives that only drop their ending before masculine nouns, grande shortens to gran before any singular noun, whether it is masculine or feminine. For example, una gran idea (a great idea) or un gran ballet (a great ballet).

Could I use reparto instead of elenco here?

Absolutely. Both elenco and reparto mean cast (as in the performers in a production) and are completely interchangeable in most Latin American countries.

I always forget the difference between ese and aquel. Why use ese here?

Both translate to that, but they show different distances. Ese is used for something relatively close to you or just mentioned in conversation. Aquel implies something far away in both space and time, like saying that ballet we saw ten years ago.