Daezuel
Potato del Grande
Honestly though the fastest way to make your team relevant will be getting your Elza to max level. To do that you'll need to get as many BF units as you can (the ones that say bonus like Elza) and run the 8 energy Grand Gaia Chronicles as much as you can. Take the karma and buy up all the Gigantaurs and fuse them 5 at a time to Elza. Buy the mats for her awakening from the same source as well once it becomes time obviously.
Once you max that character you'll have a desired friend unit that can blast through the story on her own when there aren't any farming events going on.
Once you max that character you'll have a desired friend unit that can blast through the story on her own when there aren't any farming events going on.