Looking at your team, I'd say that you will have problems with:
- Chuck
- Clair (Ice Beam, Thunderbolt)
- Misty (Thunderbolt)
- Sabrina (Bug Buzz doesn't do much damage since it is Special, and they are Specially defensive.)
- Blue's Gyarados (Thunderbolt)
- Will's Xatu and Slowbro
- Karen (except Vileplume and Umbreon)
- Lance
- Red's Blastoise and Lapras
hmm... You need to alter your team a little bit. Camerupt is a bit useless here as it overlaps types with Gastrodon and Typhlosion. I suppose Forretress is useless in-game, but it is up to you whether you should use it or not. You can give Ice Beam to Gastrodon.
Typhlosion, Gastrodon and Forretress are fixed for your team. I would like to make a lot of changes in your team. Here you go:
- Leave Yanmega and get another Flyer such as Fearow. You need Fly HM to move from one place to another easily. Useful moves for it: Return, Fly, Drill Peck and any other move. You can catch a Spearow very early.
- Options for 4th 'mon:
- Heracross: Megahorn, Brick Break, Earthquake, Rock Slide / Stone Edge / Rock Tomb. It is extremely useful for Will, Karen, Pryce, Sabrina (I doubt though), and Red's Lapras. Headbutt trees in Ilex Forest.
- Weavile: Night Slash, Ice Shard, Brick Break, Poison Jab / X Scissor. Plays same role as Heracross, but is a little frail. Sneasel is obtained in the route 28.
- Primeape: Cross Chop, Assurance, Rock TMs, Thrash. Sabrina wrecks it, but other than that it is good.
- Ampharos is definitely your sixth 'mon. It kills Water types very easily, and is a great team mate of Typhlosion. Thunderbolt, Thunder wave, Signal Beam, Light Screen. It also supports your team (Heracross and Weavile) against Sabrina with Light Screen.
Good moveset for the rest
Typhlosion:
- Lava Plume / Flamethrower
- Sunny Day
- Solar Beam
- Focus Blast / Hyper Beam / Eruption
Gastrodon:
- Surf
- Whirlpool -> Waterfall
- Mud Bomb / Earthquake
- Recover
Forretress:
- Strength
- Gyro Ball
- Bug Bite / Toxic Spikes
- Explosion
Hope this helps :)
