"I think we agreed on the team that the ultra-hard NES version would be difficult to sell nowadays, and many sections look very dated by now. We looked at all the other Battletoads games and I think we even had the arcade board running. We wanted to keep many of the features that people remembered positively of the games, while trying to focus the gameplay on some consistent mechanics to avoid frustration. Overall it was a big relief for me when it was cancelled. Developing on GameBoy while Rare was still owned by Nintendo was hard enough and I often felt like a second class citizen. Getting any resources to make a good GameBoy title would've been even harder as a 3rd party developer for a competing platform." - Former RARE dev
As we all know, Battletoads for the GBA was cancelled. We've posted up the footage of this project in the past, and it seems like the cancellation was a good idea. The project wasn't really looking up to snuff.