Using ZSH ZMV To Mass Rename Files Episodes

This presumes you are in the show folder looking at all the season folders AND the shows have the following format:
### - Episode Title.mkv

zmv 'Season (*)/([0-9])(*) - (*).mkv' 'Season $1/{showtitle} - S0$2E$3 - $4.mkv'

This should leave you with:

Showtitle - S01E01 - Episode Title.mkv

...and so forth.

If you are unsure, add the -n flag to zmv and it will present you the changes versus simply making them.

Note: Replace {$showtitle} with the title of your show. Nested directories with zmv gave me trouble so consider this the one bit of lifting required to save you a bunch of time.