Thanks for playing! I did want to add a melee, and it would be easy to implement, but there just aren't enough buttons. The Game Boy Color doesn't have trigger buttons, so I can't map to those. Additionally, while each mechanic is easy to implement in a vacuum, its adding everything together cumulatively that can have an impact on performance. I had to think critically about which mechanics to cut in order to preserve smooth gameplay within the limits of the GBC.
I think the project is pretty cool and I hope you are getting a lot of love from the community! You're right the game boy color does not have enough buttons, but maybe this project has potential being turned into gba advanced game one day and be able to handle more ideas you get. But I'm just a fan who doesn't know how that coding works tbh