Multi-Franchise Match-ups!

If each and every piece of media is counted, Sonic has run faster than the speed of light whereas Dash can hardly keep up with a car.
But, only counting the Sonic games and the Incredibles movie, they would appear to be equally matched.
Both can run on water, and both can use their speed to their advantage when it comes to combat.
However, all of Sonic's speed comes from his shoes, which triple the speed he can run at. Dash's power is pure natural ability.
So, my vote goes to Dash for this round.

Where did you learn the thing about Sonic's shoes making him faster?

An episode of Game Theory about how fast he can run.

Oh, I would say Sonic still.

Sonic