The best way to dodge it is to go to the edge of the arena. When you’re there, you only need to worry about 1 line of fireballs, which will be on the floor. There are 3 different ways the fireballs can be arranged.
1. A single fireball rolling at ground level. Jump over it.
2. 2 fireballs stacked on top of one another, starting from ground level. Either jump or double jump over it, or shadow dash through it.
3. 2 fireballs, 1 at ground level, then one above it with a gap in between. Jump, then dash through the gap when you are in the right place.
The hardest pattern to deal with is the 2 stacked followed by the 2 with a gap. If you jump over the stacked ones, you need to immediately run back to the wall, then dash through the next line. If you dash through the stacked ones, you’re probably going to get hit, but try running back to the wall anyways. If you get hit at any point, go to the ground, and get ready for the next wave. I’ve found that if I panic, I end up getting hit a lot more.