Well, yeah, this team has some major flaws, i'll indicate them in this answer. For starters, you have no EVs, so it makes this hard to answer. I'll try my best, though.
Torterra. Well, he's a supreme wallbreaker, and you got almost all the moves right. Problem is, you got the Nature is messed up. I suggest this set:
Torterra (M) @ Choice Band
Trait: Overgrow
EVs: 252 HP / 252 Atk / 4 Def
Adamant Nature (+Atk, -SAtk)
- Wood Hammer
- Earthquake
- Stone Edge
- Superpower
Yay for CB Torterra =D. This guy wrecks havoc and his dual STABs are almost unresisted in NU (Damn you, Altaria and the others!). Wood Hammer is his primary STAB and OHKO'es when unresisted. Earthquake is his secondary STAB and hits everything that Wood Hammer doesn't hit neutrally (Steel, Fire, etc.). So his dual STABs are entirely walled by Flying types. That's where Stone Edge comes in. With Earthquake, it makes the EdgeQuake combo, and the three former attacks are now officially UNRESISTED in NU. Superpower is just a back-up plan.
On to Armaldo. Hardly anybody uses it without Rapid Spin. Plus, Slash has a mediocre base power and is thus never ever seen in competitive. Even though this is in game. But still, Slash is terribad.
Armaldo @ Leftovers
Trait: Battle Armor
EVs: 252 HP / 252 Def / 4 SDef
Impish Nature (+Def, -SAtk)
- Stealth Rock
- Rapid Spin
- Rock Blast
- X-Scissor
Rock Blast actually isn't bad, as it breaks through Subs. Well, the rest, you can figure out as it's a basic Rapid Spinner which sets Rocks.
Golduck is not a very good Water sweeper. If you want a really good Water sweeper, try Gorebyss.
Gorebyss @ White Herb
Trait: Swift Swim
EVs: 252 SAtk / 248 Spd / 8 HP
Timid Nature (+Spd, -Atk)
- Shell Smash
- Surf
- Ice Beam
- Hidden Power [Electric]
Basic Shell Smash sweeper. Have fun sweeping.
I actually don't want to replace your whole team, so we'll be keeping Monferno. Plus, I never used him before so it's something new for me =D.
Monferno @ Eviolite
Trait: Iron Fist
EVs: 252 Atk / 252 Spd / 4 HP
Jolly Nature (+SAtk, -Atk)
- Swords Dance
- Mach Punch
- Fire Punch
- ThunderPunch
After one Swords Dance, Mach Punch can be deadly. 'Nuff said.
On to Altaria. Lum Berry is totally useless. Like, completely. And Dual Status is really not his thing. Even less Walling. Plus, Walling in-game will lead you to nothing. In-Game is always total offense, full restores and passing Speed Limits on your Bike. So we'll convert him into an Offensive MONSTER.
Altaria (M) @ Choice Specs
Trait: Natural Cure
EVs: 64 Spe / 252 SAtk / 192 HP
Modest Nature (+SAtk, -Atk)
- Draco Meteor
- Fire Blast
- Hidden Power [Ground]
- Rest
Specs 'Taria. Not much to say apart from the fact that he'll be tearing apart every Pokemon.
Ampharos (F) @ Light Clay
Trait: Static
EVs: 248 HP / 8 Def / 252 SAtk
Modest Nature (+SAtk, -Atk)
- Light Screen
- Reflect
- Discharge
- Hidden Power [Ice]
Dual Screener needed.
Well, I rated your team. Hope I helped you!