Terranort is such a bum. I find it's easiest to level grind before the final episode. There's that round area in Radiant Garden where the trio fought that boss together, and you can just keep going there and spamming Mega Flare and nuking everything.

I'll do all the things if I like a game enough/they're doable with some effort. But just to get the story content, I'm not keen on.