Hey what's up it's your favorite
virgin Care Bear expert here. From here on, I'll be using OG and 2019 respectively to refer to them.
Alrighty, so their Care Bear Stares are ultimately non-factors here since they both resist empathic shenanigans. Additionally, neither fit the series' criteria for being evil, so the purification/powernull aspects of the CBS won't come into play.
Both can fly by creating clouds to float on, and both can create miniature storm clouds to try and zap the other. OG is a bit superior in that regard since his will follow 2019, but he can always get rid of it with his own Belly Badge power.
OG's biggest advantage is his ability to
send people to Care-A-Lot with a thought. He himself has never used this ability, but it's nonetheless something he should be capable of.
That being said, 2019 is exponentially smarter, craftier, and more creative than OG. Upon seeing that his CBS won't work, he's going to try and think his way out of it. He's much more likely to run, hide, and set up some Bubble Mines to trap OG and let him float away than OG is to BFR.
So, my vote is that 2019 Grumpy wins with mid to high difficulty.