By battling him? lol
Buy a load of potions and pp ups and revives. Obviously use your strongest Pokemon then DESTROY him
defeat the Elite Four at the indigo league
Lorelei- ice Pokemon Bruno- rock Pokemon Agatha- physic/ghost Pokemon Lance- Dragon Pokemon Last your rival Gary
when you beat the elite four and have 100 Pokemon go to professor oak and he will give you and Gary the national dex
Gary is or what ever you named your rival. He will have the Pokemon that is the strongest against your starter. Hope this helped!
you battle gary
defeat the Elite 4 and after that, Gary.
blastoise
it is to the left of viridian city-where you defeat Gary for the first time
the groomer in fire red is in pallet town the groomer is gary's sister.
The same Pokemon as you, as you are Red in Fire Red. Your rival is Blue/Gary.
Your rival, you've fought him before so you know his weaknesses.
The champion is Lance. He is defeated by Gary. (or who you call your rival) If you defeated Gary in the last battle you are the champion.