if you saved after you lost then you have to start the game over, that happened to me.
enter the Pokemon league
Only if you beat the Pokemon league.
At The end of victory same Place as white
You will have a Magmar.
I think the Sinnoh league
Beat them again
beat the Pokemon league
You can buy them in the Pokemon League Pokemon Center.
Ghestis disappeared after you battled him and N at the Pokemon League.
nothing you start again
First you have to complete all Gym Leaders & get all of the badges. Then you head to the Pokemon League.
If you havent beaten the Pokemon league then level them up a bit then defeat the Pokemon league
you catch it when you go againest N at the Pokemon league
free roam
In the Pokemon League in the Champions room.
enter the Pokemon league
after you beat the Pokemon league