Silver Got Served - 30G (Original Achievement)
To get this Achievement, you must defeat Silver the Hedgehog.
To get to Silver, you must clear all of Area 3 (Crisis City, Rooftop Run, Planet Wisp) and make the Challenge Gates appear. This will cause Silver to appear above Crisis City.
In battle, you can only hit him during a few of his attacks.
1. Silver will pick up a single car/object and throw it at you after a little while. Simply jump and homing attack it to knock it down.
2. Silver will pick up 5 or 6 cars/objects and will throw it at you after a while, once again simply use homing attacks to jump from object to object to get to Silver and attack him.
3. Silver will hold 3 cars/objects above you, one of them will drop first before the other two. Simply wait in the middle for one to drop, then run to where it was to avoid the other two.
4. Silver will bring together a ton of cars/objects to create a ramp of sorts and throw it at you. You must jump onto the ramp and boost along it, then jump and homing attack Silver when you are close to him.
5. Silver will create a knife out of his energy and will throw it at you after a set amount of time. This knife is either horizontally shaped or vertically shaped. If vertical, simply dodge it by side stepping with the bumpers. If horizontal, simply jump over it.
6. After you attack Silver enough he will use his final move Meteor Smash. He will create a giant ball of cars/objects and have it chase you non stop. Meanwhile he will either attack you with psycho knives or try to drop an object on you that you must dodge with the bumpers. Once you get close enough simply homing attack Silver to send him back into his own attack and finish him.
Below is a video of mine to sum up what to do. Omochao also explains it.