Funny story, I actually thought up one of these just for kicks. Not sure how accurate it is as to its effectiveness for Robin, but I imagine it wouldn't be half bad.
Wizard Island
Platforms: 2-3
Platform Distance: L
Distance: XL
Slope: L
Top: S
Side: XS
This is the theoretical best stage for Robin (in my opinion). It would be a flat stage with platforms hanging halfway off both edges of the stage. Similar to the ones in Town and City, but maybe lower. An optional third platform high in the middle could assist aerial recovery and aerial combat. A long stage distance ensures time to charge Thoron, made easier by the platforms on either side. If the platforms are long enough, and you are fighting the enemy on the platform, you could land a Sbair to kill around 50%, or a Fsmash around 30%, thanks to the short sides. The empty center, devoid of platforms, will ease hitting with El, Arc, and Thoron, and helps ensure Arcfire remains an obstacle in reaching you. The long, steep slopes to either side make recovering a breeze, recovery so quick and variable that stage-spiking would require delicate timing. Edge recovery is made much easier with the platforms. The closer a stage is to Wizard Island, the better it will be for Robin.
