I love this a lot!
I think this is a beautiful love letter to Donkey Kong '94 and other titles for the Game Boy. It perfectly captures the essence of the console through high-quality sprite work on both the characters and backgrounds and it overall looks so charming! The music is also fun to listen to and really fits the retro feel.
Poy Poy really shines through its simple, yet satisfying gameplay, though. Gaining power-ups by jumping on enemies is a cool idea that sets the game apart from Donkey Kong. The level design is also great, with its puzzles being cleverly designed around the movement and power-ups in a way that tickles your brain.
Maybe the jump could've been less heavy but it still works with the level design, and I did encounter a few glitches that could've been fixed with more development time (this is a Game Jam entry, after all), but really nothing game breaking.
Overall, this was a brilliant entry and you guys did an amazing job making it. Keep up the good work!