In need of a new Pokemon Fire red/Leaf Green competitive team

Ok back when my friends and I had a casual tournament i beat them all with the team of
Gengar
Charizard
Lapras
Jolteon
Arcanine
Snorlax

The team had 0 focus besides just throwing out powerful moves and making the enemy team faint. Now we are having another tournament and since then my friends have gotten somewhat into the competitive scene of Pokemon and i don't want to get decimated. Can you guys give me a new team or even fix up the one i have already. I am willing to catch, get specific nature, ev train new ones, as well as go item hunting. Even willing to start over for a new starter. The only limitations is that i am restricted to only the pokemon in fire red and/or leaf green and i cannot use any legendary pokemon. Everything else is fair game 8)

I'm not much into competitive play, but I think you have a very nice team. The only problem I see is that you have 2 fire types.
Maybe you can switch Arcanine for a fighting type. Hitmonchan is a good Pokemon. It can learn Thunder Punch/Ice Punch and cover it's Flying weakness.
Or you can get a grass type. Victreebel or Vileplume. They may not seem much, but they learn moves that poison, paralyze or put to sleep. My friends always have a hard time beating my Venosaur. It would be great if you could trade one.
Another great Pokemon you can use is Nidoking. He has a great movepool.

I hope I helped!

i recommend swapping that charizard out for a venusaur or an other grass type, 4x weak to rock is dangerous.