Overwatch on Switch, I feel, could easily have Nintendo skins.
Some of my ideas:
Winston - DK
Pharah - Samus
D. Va - Samus/Zero Suit out of mech, Arwing/Fox out of mech
Junkrat - Bowser Jr., Waluigi; would have a bom-omb launcher and a Banzai Bill themed tire.
Roadhog - Bowser, Wario; would have a chain chomp hook.
Tracer - Inkling; The hair for the Splatoon 2 posterboy + the Dualies
Also, I think one of the Omnics could have a R.O.B skin; but it would be more R.O.B inspired, due to his shape.