What happens next is best described as an interlude. There's a panel vignette with all the Robot Masters coming home for repairs and consolation.
Duo: That's the end of the story, right? Mega Man defeated the Stardroids, Sunstar retreated somewhere, the Robot Masters returned home to ask for repairs...
The vignette shows Duo sleeping under a tree. Every time he finds himself on another planet, he sleeps wherever he happens to be.
Duo: However, I... I can't help but feel like... Something's wrong...
The vignette fades to white. Every time something fades to white, you know there's some dreaming to be had here. In this case, Duo appears to be dreaming about his place of residence and employment, Star Manor.
Star Manor Dreamscape Overworld BGM: Dark Clouds over Hyrule (The Legend of Zelda: A Link to the Past)
Duo: Hm, that's strange... I can't believe I'm back here again.
Walking forward a little bit pans the camera towards the big doorway, wherein Mercury is seen walking just past it.
Walk forward some more, closer to the doorway. The controls lock up once you hear that same "splat" sound Mercury makes when he walks rather than Duo's thunderous thumping. A very short panel vignette involving Duo finding something very slimy under his foot begins!
Duo: Gah!? What the!?
Mercury then shows himself, sliding out from under Duo's foot.
Mercury: How do you figure, Duo!?
Duo: The better question is, how did you get in here!? I'm gonna report this to my caretakers!
Mercury: Ha, good luck with that.
Try to walk back towards the main entrance. You'll find they lock up when you walk just two steps back.
The camera pans to Venus, who's standing in front of the two grand doors.
Venus: Aww, you thought you could escape, didn't you?
Then it pans to Jupiter, who's flying in front of the left railway.
Jupiter: There's 10 of us...
And then it pans to Pluto, who's opposite to him.
Pluto: And only one of you!
Duo: Alright guys, you're about to make me do something I'll seriously regret...!
Terra: Like what, destroy the building or lose to a band of outlaws?
Duo: Bring it on!
Star Manor Dreamscape Battle BGM: Final Boss: 0 (Kirby's Dream Land 3)
Duo has the following moves:
Duo grabs the enemy with his enormous left hand. He seems to use it on robots he deems suspicious.
Duo rolls around into an angry ball of alien energy. This leaves him Dizzy afterward.
Duo uses his jetpack on his back to ram himself headfirst into the enemy. Clear the way if you're on his good side.
Duo flies sky-high for a turn. The next turn, he crashes headlong into the enemy.
The other Stardroids have all the same moves. They're just a level higher than when Rock was fighting them, and they don't give any sort of EXP reward, because after all 9 Stardroids have had at least 2 turns to act, Sunstar interrupts the battle.
Sunstar: Alright boys, you've had your fun! Now it's time for me to deal with the pest...
The battle ends. A panel vignette is shown, with Duo looking injured and upset.
Duo: N-no, p-please...! H-have mercy...!
Sunstar: I'm afraid not. It seems myself and mercy don't make a very good combination!
The light from the Nova Weapon is so strong, it covers the entire screen in a matter of milliseconds. The resulting fade-in comes back to the earlier vignette with Duo sleeping under the tree. He then wakes up in... W-well, I wouldn't say "cold sweat", since robots don't sweat...