>What is a Nuzlocke?
Nuzlockes have three rules - 1) First encounter in an area is your only capture, faint or don't like it? tough shit 2) If a Pokémon faints, it's permaboxed or released. 3) Nickname every Pokémon. Other rules can be added - most people, for instance, play with a dupes clause to prevent having a team of five Zigzagoon. More info on additional rules and variants below.

>Is [insert thing here] acceptable?
You can do whatever you want. As long as it follows the three rules, it's a Nuzlocke. Feel free to add additional challenge if you want. It's your game.

>Is [game/romhack] hard?
Probably. There's a ranking list of mainline games below. Most romhacks will be as hard or (likely) harder than that, some are borderline impossible.

>Nuzlocke info
https://pastebin.com/8b3rHGuX (embed)
>Nuzlocke generator
https://nuzlocke-generator.herokuapp.com/
>Links to official games
https://pastebin.com/7z6UNHyB (embed)
>Romhack links
https://pastebin.com/GzWfs9Bz (embed)
https://pastebin.com/GfJ9zhqx (embed)
>Emulator info
https://pastebin.com/qRSUUHF7 (embed)
>Difficulty list
https://pastebin.com/xm8qF0fy (embed)
>Pokémon Nuzlocke images
http://www.mediafire.com/file/sxu318m9an5ulbm/
>Pokémon Bank sprites
http://www.mediafire.com/file/ueadxvt1f52m0md/
>Additional templates
http://www.mediafire.com/file/vmfck3jdowgn472/