I have yet to get to the post-game stuff. I can easily get to the sixth area, but there's this aggravating flight challenge issued by Korin. I cannot get past that one no matter how hard I try. You have to somehow fly through 23 rings, and I can only get through 20 of them due to those stupid magnetic orb things that slow you down AND make you have to fight to fly straight. There's no way to get rid of those orbs, either. I tried performing a Ki Burst, but it did nothing but attract unwanted attention from NPCs flying nearby.
Is it mandatory to complete, or just an optional side-quest? Hopefully it doesn't unlock anything...
Then again, there is probably some trick to the flight challenge that negates the problem of those magnetic orbs. There usually is some little trick to otherwise aggravating tasks in video games.
EDIT: I've finally finished the main story, and am now starting to dig into the MUCH larger post-game content. I also fused Zed with Super Saiyan Pinich, to form a new, MUCH stronger warrior I nickname "Zenich". (It's a pun--it's both a portmanteau of Zed and Pinich, as well as a corrupted form of "Zenith"--as in, there's NOTHING stronger in the entire multiverse!)
Lucky for you that flight challenge is a side quest that rewards you with...EXP. So totally optional. And yes i know how aggravating it is, took me 4 tries to complete it. if there is a way to negate the gravity orbs i didn't find it, i simply powered trough them
I only just started the post game myself, did the quest that fully unlocks Dragonball finding and Shenron summoning, beat Frieza and Cell and am looking for side quests to complete. Fusion wise i'm trying to fuse all my "Android" avatars into cooler looking androids