Hey so i might be able to help you out here a bit. I've been playing Robin in a Robin/MK team for a few months now.
The main early kill options are MK's uair string --> up b and, of course, Robin's checkmate (dthrow --> uair), so make sure you both can do them reliably
For things that can combo into MK's up b you've got:
- uthrow
- arcthunder --> uair
- arcfire --> uair
We're planning on labbing ways to combo into MK's uair string some time soon, so I'll let you know what we find when we do it.
For things that can combo into Robin's uair (or any other aerial, depending on the situation), there's:
Now, a quick note about MK's uthrow. He has a hitbox on his way down during the throw, this hitbox is very, very strong. Make sure you do not get hit by it. It starts to kill Robin at around 80% from the centre of the stage (No DI).
Although, you can use this hitbox to your advantage. There have been many times when we got a kill because he uthrow'd me and we hit someone. Be creative.
Some nice and effective low percent combos you have:
- M dthrow --> R bair --> M bair
- R fthrow / bthrow / arcfire / arcthunder --> M tornado --> R uair / fair / bair / arcfire
I'd recommend learning how to combo from MK's tornado, since it's kinda difficult, but very worth it.
Finally, if you're looking for a stylish 2v1 0-death, I put this video up a while ago:
https://youtu.be/3o3-ITeWLkY