MY STRATEGY
WILL
Gengar lead using Shadow Ball for Bronzong, Jynx, Grumpig, Slowbro and Grardevoir.
For Mega Alakazam was my pokemon slow, so I let my Gengar die, and switched to Dragonite and used Dragon Claw.
KOGA
Dragonite lead using dragon dance 5/6 times versus Skuntank.
After that, Dragonite lead using Dragon Claw for Skuntank, Venomoth, Toxicroak, Muk and Mega Beedrill.
For Crobat, Dragonite can use Thunder Punch or Dragon Claw.
BRUNO
Gengar lead using pyschic for Hitmontop and Hitmonlee. Then he switches to Dragonite and uses dragon dance 5/6 times verus Hariyama.
After using dragon dance 5/6 times, Dragonite uses Dragon Claw for Hariyama, Mega Lucario and Machop.
KAREN
Dragonite lead using Dragon Claw for Weavile and Absol.
After that, he uses dragon dance 5/6 times versus Spiritomp.
Then he uses Dragon Claw for Mega Houndoom and Thunder Punch or Dragon Claw for Honchkrow.
LANCE</B><B>
Dragonite lead using dragon dance 5/6 times versus Charizard.
After that, Dragonite uses Thunder Punch for Charizard, Gyarados and Altaria. For Garchomp and Mega Salamence, he uses Dragon Claw
hope this helps if you still struggle :)