Hi! I'm new here...... How do I beat Bizarro Sephiroth?

Here is a nice trick I figured out to kill him all in one go.

Use Knights of the Round and he will die after the attack.

I forgot to add that the core will receive no damage during this but he will still die.

In case you don't have Knights of Round yet, you can do it this way.....

When using two teams, have the first team eliminate the left magic and the head, then switch teams when given the chance.

With the second team, work on the right magic and head, that will make the cores defense drop.

Have team two destroy right side of core, then switch back to team one, where the left cores defense should be down.

Attack the left core until its destroyed, then focus on the torso.

Man, he is so easy! To defeat him easily, get the ultima materia.

To get it, you probably would need the enemy skill: Laser (Halves lives of enemies).

After Cloud gets sick, Cid becomes the temporary leader, Cait Sith says that you need to get the huge materia before Shinra does. Go to the path eading to Corel, the path were the corel mako reactor was built. When you get on the train, defeat the enemies on the cars.

When you reach the 2nd final car, you should fight an iron giant. Use laser on him a few times, and he'll be pretty easy to kill. After him, you should fight a robot eagle. Do the same; laser on him a few times. Then defeat the 2 soldiers. After that, you should stop the train. If you succeed, a boy will give you the "Ultima" materia.

You won't be able to use it; it has to be lvl 2 if you want to use it. But if you fail on stopping the train, it will crash into Corel. Then the boy will give it to you, for a price. Ultima does around 5000 damage.
Keep using it on bizzaro Sephiroth, and he should be a dead duck.