OK to start off with i am a girl so if you don't take info from girls then back off.
this is the team i had
a level 65 charizard
a level 55 pidgeot
a level 70 or 65 kadabra or alakasam
a level 62 dragonite
a level 50 jolteon train at evee then at level 50 evolve
and last a level 40 lapras actually you could have it anywhere between 40 and 60
You beat all the gym leaders then the elite four
you have to beat the elite 4 and then you battle them you have to beat the elite 4 and then you battle them
he stays in the elite four as champion
with skills :>)
uuuhhhhh..... no..
no
One island.
The same you can do in Fire Red.Read my answer to that here:What_can_you_do_after_you_beat_the_elite_four_in_pokemon_fire_red
Nothing
against the elite four infernape will do very good with its fire type moves but since the first gym is ground it is not so easy to beat it with a fire type. i beat the elite four 6 times with my infernape. the beat moves for it are fire blast and flame wheel
Fire and water are the best combination to beat the elite 4.
See question "Is this a good team to beat the elite four"'s answer.