Battle is 10 races i cannot help you though because i haven't played for a while

In Challenge, Brake Link is introduced, but this track isn't ordinary. You have to brake. For me, I let go of gas, then ATTACK like crazy. Spinning makes more problems. In Battle, Brake Link gets harder and a little trickier. In Violence, Black Shadow is your opponent. Brake Link III is the hardest. However, you really don't need a rocket start, or to hit dash plates. All you need is to play and watch Shadow die.

I always find the "Death Race" with Beastman to be the hardest. 

Anyway, Battle Mode has the same 10 Races.  Just you VS them in a random order. 

Mr. EAD's Mission is pretty easy if you take the right path, then the left, after that, smooth sailing (providing you don't hit the wall hard).  The best bet is to pratice that track in Time Trial Mode. 

If your aiming to get a good time in Battle, your only option is to use "Dr. Clash", since that Mission gets replaced with a Mission with Guster and is only a one lap race on a different course.

As for beating Dr Clash's Mission, which was one of the Fire Field levels (one of the easier ones if I remember correctly), go and pratice in Time Attack mode.     

@customracer209: The Violence Missions are random as well as the opponents.  The game gave a me a Death Race with him once on the last mission.   Failed because of him.

For me, Death Race is easy. All I have to do is try to attack him, but once, he simply killed himself. However, I show great dislike for the speed limit missions, especially when using machines like Golden Fox (cause getting rocket starts are near impossible)