Impressive amount of work, 80 monsters? That's so much!
* The music was extremely short / repetitive at only 8 seconds per song, but really I do appreciate having the ability to toggle it actually programmed in since I played this on console
* End of combats felt pretty abrupt, maybe a little win jingle would help. It's very easy to spam attack and skip right past the win/lose messages. Similarly I was shocked when I suddenly died and respawned because the message "cinderkit returns to safety" was very easy to skip through, I thought maybe the game had crashed or something for a moment.
* I miss having distinct sounds for monsters like Pokemon does, I don't know how difficult that is to pull off on NES but that kind of thing adds a lot of character to the creatures
* The pixel art on the monsters is fantastic!
In the end I think it was a cute pokemon clone and doing true NES development is a feat in and of itself, good work!