fighting dojo
No. But, you can fight them (as gym leaders) In Pokemon Silver/Gold.
With your pokemon... noob
you can't. you can only fight the Pokemon league again.
You can't fight them again if you go to their gyms. But to fight them again you have to go to the Survival Area and gain access to the place near the Pokemon Center and some of the Gym Leaders will be there.
You cannot fight the Gym Leaders again in Pokémon Black after defeating them and being awarded their Gym Badges.
It might depend on the Pokemon, though usually you can face legendary Pokemon again if you beat the Champion.
yes beat the indigo plateu again
nothing, you can fight him again.
Never because match call doesn't exist in sapphire.
beat the elite 4 again then go back to Mt Silver
After you've beaten Brock go beat the other six leaders then you can fight Blue
you need to beat the Pokemon leuge and then get their phone numbers by asking or doing somthing in the town