The four Grass Energy are essential because they make a Jet Sonic with only basic energy entirely more possible. This really helps late game if you've got a few random energy attachments scattered around your field.
With only three Lightning Energy, although it does lower the viability of using assault laser, I've found no apparent struggle in getting the right energy out at the right time.
(can't really say the same thing for getting DDE's out though)
However, I haven't really experimented much the other way yet either. It's worth a shot though, given Manectric-EX's use against things like Jirachi and Aegislash.