Are we allowed to also use the NES NTSC color palette or are we only strictly allowed to use the NES color palette? 

Feel free to use that palette. We're not too strict on the colors. The palette provided in the resources is just an example.

Alright thanks for the info homedog

There are a few more options, but these are only mild variatons of the NES palette (mostly the same with tone variations).
https://emulation.gametechwiki.com/index.php/Famicom_color_palette