I think it would be really cool to be able to make levels where the power-ups works like in older games. While it could be hard-coded as a "make it like JellyCar 1" switch, it might be neat to have toggleable settings for each power individually. So, for example, I could make a level where "grow" is unlimited (like JellyCar 3), and "signal" is on the recharge system (so I can use it for a few seconds, but then I have to wait for it to recharge - much like how "grow" worked in JellyCar 1).
(But honestly, even if it is just a "make it like JellyCar 1" switch, that would still be great.)