I would get a rock or ground type and use dig or teach one of your Pokemon dig
Kill them with Fire.
Defeat the 3rd Gym Leader, Wattson, in Mauville City.
Flash, I believe.
ground. He is an electric type.
You Go left and use rock smash to open up the tunnel
You use your strong(est) Pokemon to kill the Gym Leader's Pokemon.
Maylene (Veilstone City) uses Fighting-type pokemon. Use Flying or Psychic-type pokemon to defeat her. Wake (Pastoria City) uses Water-type pokemon. Use Grass or Electric-type pokemon to defeat him. I put Maylene and Wake on here cos you can battle both of them third.
Whitney ,she's at Goldenrod City.(Normal-type)After you defeat her she'll start crying.Talk to the nearest player and then talk to her and you'll get your badge.
I am working on the same thing I will tell you when I finnish
Machop- Level 17 Makuhita- Level 18 train a wingull and a taillow until they both get wing attack. It will easily defeat the machop and makuhita
3rd gym
I have Pokemon platinum the 3rd gym leader always their your probaly just not lucky.