Well according to Sonic Unleashed, Sonic is capable of running at over 2500 MPH.
Diesel, in contrast, is a BR Class 08 diesel-electric shunter which, depending on the design variant Diesel is, would have a maximum speed of either 15 or 20 MPH.
I think it's pretty obvious that Sonic would win in this situation since he could probably run so fast he'd completely destroy Diesel just by the soundwaves produced as he runs past him. Only way I could imagine Sonic not winning is if he literally stands on the tracks and just lets Diesel run over him.
Sonic can run at the speed of sound, right? Well, Orion can be faster than light but needs to be flying to do so (I call it hyperspeed). Sonic and Orion are both pretty agile, so there’s probably a draw there. Orion is able to zone out Sonic with various weapons, but ranged weapons are not going to defeat Sonic alone. Sonic is faster than Orion on the ground, but Orion has good reflexes and could block some attacks.
I haven’t developed all of Orion’s powers yet but from what I’ve developed there’s probably a draw there.
Also for the user below me, you can ask me Orion’s powers via PM or my Ask Thread.