There are three primary legitimate reasons why someone would search for a decrypted Pokemon Y ROM.

: Emulators cannot "break" Nintendo's encryption on the fly; they require the data to be readable.

You place the encrypted file in the same folder as the tool.

To understand the value of a decrypted ROM, one must first understand how Nintendo protected its software. Commercial 3DS games released on cartridges and the eShop are encrypted. This encryption ties the game file to a specific console or Nintendo ID, serving as a digital lock to prevent piracy and unauthorized distribution.