When you get to the end of the victory road in pokemon white or black, you will fight with cheren, your main rival. He will be quite strong (he will have his main pokemon at level 65 and all others at 63). To beat him, just use type advantages or use pokemon higher than 63 in level.
enter the Pokemon league
The cave cave u take to go to go to the Pokemon League
Cheren is a guy
Victory road
beat Cynthia at undella town complete unova and national pokedex get dive and go into the abyssal ruins at undella bay find the seven sages and find and beat cheren and bianca one more time.
Nope
No you dont have to.
If you are referring to the old GBA games, then yes and no. You have to beat the Pokemon League in Ruby and Sapphire to get Rayquaza but in Emerald you can get him before beating the Pokemon League. Hope this helped.
yes
Cheren is in the last room of Victory Road before going to Victory Road. (Meet him on Route 5 first.) Bianca is in Professor Juniper's Lab. (I think after beating Alder, I'm not sure)
Cheren will be at the end of victory road.
Yes, you beat the Pokemon League first.