Yaris

This is pretty much it. Once you beat this guy in track 8 you have won the game.

My only advice to you is to RIDE UP THE SIDE OF THE WALL. So just keep to one side (either all the way on the left or right side) and you will avoid 95% of the danger and you can finish the track pretty easy.

Just ride up the wall and never stop firing at him.

If you want, you can do this in multiplayer. Simply get a boosting partner and tell him not to do anything so you can beat the bot. In multiplayer, you have unlimited lives. If you've never played multiplayer before, you'll actually get 4 achievements since without your partner doing anything, you'll easily win. I personally did this in a regular match when the game was still available.