I don't have much Falco experience, but I do know that you should play the beginning of each stock the same way that Fox plays against Pikachu (don't get grabbed until you're at a percentage where it won't give Falco a free 60%). Seems like this is one of the few match-ups where you can rely on good reaction time. If you ever see Falco doing his side-B, short-hop neutral aerial, and if you react quickly enough, you'll always be fine (as long as you are prepared to space away if he cancels it any).
I forget what the frame data on Falco for a chaingrab was? Did we have like a 3-frame window or can Falco always get out of it even with perfect timing? If the CG is guaranteed, then this MU seems to come down to who can grab whom first. With Falco, it's a lot of free damage, and with Yoshi, it sets up nicely for a gimp (especially on a flat stage or one with a walk-off like Castle Siege). I'm pretty sure Falco can camp harder than Yoshi and it's not easy to approach, but I do know that if you get hit with a laser, the hit-stun on it is pathetic and you can attack almost immediately after getting hit, so unless Falco is literally right next to you (and he shouldn't be lasering at that point), then you shouldn't get grabbed or attacked following a laser if you attack him back or jump away or something.
I think Falco's got the MU about 60:40, possibly worse, but I'm open to be flexible as the discussion progresses and after I've played Gnes and Ozz.