One thing we do not explore much in the MU vs. Snake is... Double Team.
Seriously Mortar, Grenade, NAir (sometimes), and probably some other stuff we could easily Double Team and prevent Nade traps and from Snake pressuring our shields.
D3's Waddles are another thing we could use to our advantage. I honestly rage a little whenever I see a Lucario mindlessly throwing Aura Spheres at Waddles. Unless you're clinging with them or something you're just degrading a great kill move vs. D3. Jab them or something if you've got room. FREE MOVE REFRESHMENT. Also if both his Waddles are in hitstun D3 cannot pull out another one. If they don't know that just throw a blue ball at him during that laggy animation.
That basically forces him to approach and well... Aside from his FTilt, BAir, and Grab his approaches are pretty darn limited.
Aside from those two with the MK ban we really don't have a counter in the high/top tiers...
D3's going to be annoying if RC still remains unbanned though... Then we have to Deal with D3 on Halberd, if not there Delfino, if not there relentlessly chasing us on Castle Siege's transformations, if not there we'll get CGed all across FD... -.-
Anyone wanna teach me ICs to handle D3s? lol j/k
We are lucky though, since we do pretty well on just about any stage. Most high and top tiers have some sort of counterpick stages that they get ***** on.