HG/SS Help me Assemble my Team

(First off, I'm not remotely new to the forums - this is just a new account because I'm making a return and the other one appears to have vanished. Hello to any who may remember Angua.)
I'm having great difficulty deciding which Pokémon I actually want on my team. If necessary, I'm willing to breed or catch more in order to get a different nature or a breeding-exclusive move.
For context, I've just cleared Team Rocket out of Goldenrod and I'm yet to head through the Ice Path. I know it's late, but this is actually my first SoulSilver playthough.
To the mods: I don't intend to battle with other players competitively, this thread is only in here because it seems to be where the "rate my team" threads belong. Sorry if I'm mistaken.

I shall list the Pokémon I'm having difficulty deciding between, but obviously I haven't encountered everything yet, so if it turns out everyone thinks I should have a (for example) Jynx with me, I'd still like reccommendations on what should fill in the Jynx's eventual slot.
I plan on boosting any stats after finalising my team, because I don't want to go through the trouble for a Pokémon it turns out I won't use much.

Slot One


Lv. 46, Bold in nature (currently holding a Miracle Seed)
HP 142
Attack 84
Defense 127
Sp. Attack 94
Sp. Defense 103
Speed 109
Moveset:
Magical Leaf
Synthesis
Body Slam
PoisonPowder

Meganium's place in my team is pretty much non-negotiable. I'm emotionally attatched, and a great lover of Grass-Types, and as such I'm trying to put together a team that can support it. (I've been told Meganium are weak and don't belong in a team, but I'm just too stubborn. I'm willing to replace it with a (Grass-Type) starter from one of my other games, but that's it.)

Slot Two


Lv. 37, Jolly in nature (currently holding a Shell Bell)
HP 95
Attack 77
Defense 60
Sp. Attack 56
Special Defence 63
Speed 77
Moveset:
Aqua Tail
Dragon Rush
Twister
Dragon Rage
(Dragonair or Dragonite? Still not sure.)

Slot Three


Lv. 33, Serious in nature (no hold item yet, probably going to give it a Magnet)
HP 112
Attack 59
Defense 59
Sp. Attack 91
Sp. Defense 66
Speed 57
Moveset:
Tackle
Charge
Thundershock
Thunder Wave
(Will be replaced with a an all-special Ampharos when I get hold of one with a Sp. Attack+ nature)

Slot Four

Lv. 37, Relaxed in nature (No hold item yet)
HP 146
Attack 59
Defense 62
Sp. Attack 98
Sp. Defense 83
Speed 59
Moveset:
Bite
Water Gun
Quick Attack
Aurora Beam

Slots Five and Six


Lv. 40, Naive in nature (currently holding an Amulet Coin)
HP 96
Attack 55
Defense 53
Sp. Attack 55
Sp. Defense 62
Speed 89
Moveset:
Flamethrower
Fire Spin
Quick Attack
Payback
(Will eventually be evolved into Ninetales)


Lv. 38, Hasty in nature (currently holding a Poison Barb)
HP 103
Attack 78
Defense 58
Sp. Attack 69
Sp. Defense 71
Speed 90
Moveset:
Wrap
Acid
Poison Sting
Crunch


Lv. 29, serous in nature (currently holding a Metronome)
HP 84
Defense 37
Ap. Attack 41
Sp. Defense 53
Speed 60
Moveset:
Rage
Focus Energy
Twineedle
Pin Missile


Lv. 16, Bold in nature (no hold item yet)
HP 44
Attack 26
Defense 35
Sp. Attack 14
Sp. Defense 19
Speed 22
(Will be allowed to evolve into Sandslash)


Lv. 64, Relaxed in nature (currently holding a Razor Claw)
HP 218
Attack 117
Defense 178
Sp. Attack 109
Sp. Defense 173
Speed 103
Moveset:
Psychic
Faint Attack
Toxic
Shadow Ball
(This guy was carried over from Platinum. I'm very fond of him and I'm greatly inclined to include him.)

Two things:
You definately want an Ampharos.
And if you're going to have Gyarados or Vaporeon, don't use both. You'll have too many Pokemon on your team weak to Electric-type moves.

Thanks for that, I'll let it evolve.
Don't worry about the Gyarados/Vaporeon, I only plan to have one, I just can't decide which of the two to use.

Personally, I used Poliwrath, but w/e.
Ampharos is going to want probably a Sp. Attack +/ Attack - nature, with all Special moves. Two I would reccommend are Discharge and Signal Beam.

This team has no real competitive value, I'm afraid. There are a insane amount of things to check out to have a team remotely viable in a competitive environment, those being natures, EVs (for Effort Values), IVs (For Individual values, also known as the thing that make people hate competitive battling), abilities, items, etc.

Abilities and Items are the easiest, just find the one that suits your Pokémon the best. For example, take Arcanine: It has two great abilities that both help it perform different roles, depending on your team needs. Likewise, choosing between the items Life Orb (more power for less chances of staying for long) or Leftovers (less power but gains health each turn, allowing a longer time alive) is crucial to make Arcanine perform as a powerful wall breaker / sweeper or bulky attacker.

Natures are the next step to think about; they boost one stat (among Attack, Defense, Special Attack, Special Defense and Speed) and reduce another. Some natures simply don't affect the stats. These are also unavoidable - A speed-boosting nature could help you gain that last little bit of speed needed to outspeed an opponent, allowing you to defeat it before it does. Same goes for Attack and Special Attack for sweepers and Defense and Special Defense for walls. Usually, you will want to reduce the stat that is the most useless for you, like Attack for a pure special attacker, for example.

Now, IVs and EVs. These are the things most people ignore, but they are probably the most important. EVs are easy to tweak; they are invisible points given to your pokémon upon defeating a foe. Usually, you will get EVs according to the base stats of the Pokémon you defeated and their evolution stage. For example, a Charmander has higher special attack with a low evolution stage, and will give you one effort point in special attack. Aggron, on the other hand, is at its higher evolution stage and has an astonishing defense, giving three effort points in defense. A single pokémon can accumulate up to 510 EVs (255 max in each stat). 4 Efforts point usually equal to one actual base stat point at level 100. Use the Effort Point spread that suits your pokémon - and its role - the best.

Lastly, IVs are also invisible digits that influence your Pokémon. each stat has an IV between 0 and 31, and each IV allows for a bonus stat point at level, and often makes the real difference in a match. They also influence your type of Hidden Power as well as its base power (between 30 and 70). These are set as soon as you encounter a Pokémon for the first time, or when you receive the egg containing this Pokémon. Since you probably don't know about these, most of your Pokémon will have poor IVs, hence the mediocre competitive value. IVs can be manipulated through very complicated methods, but unfortunately these are beyond my knowledge.

For further information, visit real competitive sites such as Smogon. You will soon realize that real Pokémon battling is really, really hard to get a grasp on and time-consuming. THOUGH THERE IS AN ALTERNATIVE :D

Several battling simulators exist, the best one probably being Pokémon Online - visit the site to download it for free, and you will be able to experience battling and hone your skills without having to spend countless hours training.

Hope it helped, and Good Luck!


EDIT: Wow, way to not read through the entire OP LotF. Anyways, keep the Dragonair and the Vaporeon, really. Flaaffy is good too.

LotF: Wow, thanks for the comprehensive reply. It's not what I was looking for, but it's still great and I appreciate the effort you went to. :)
I've been thinking of getting into competitive battling, but I never knew where to begin. I've saved your post to a word document so I can read through it when I want to try.
Okay, I'll keep the Dragonair and Vaporeon, and it seems Flaaffy/Ampharos is a good idea.

Editing OP to suit. Really, though, thanks for the help. :D

To complete the story mode you shouldn't bother much with EVs, IVs or even natures, though it really gets on your nerves when you catch a Modest Pidgey or an Adamant Abra, for example.

If you're like me and don't use TMs on your in-game Pokemon, then Sandshrew is a no-go. It only learns crap moves through level-up. It's a good Pokémon, but I'd recommend Donphan (oh wait, you can't get Donphan in SS... :( ) or Mamoswine, or Golem for Ground-types. Mamoswine will obliterate Clair's Dragonairs with Ice Shard or Earthquake (Dragonair isn't that strong as you may already know since you're raising one), but Golem's Rock-typing gives it an useful Normal-type resistance. Or, if you have the time to fish Metal Coats from wild Magnemites, you could try Steelix, which has amazing Defense and can solo Koga's team later on.

Remember that, if you want to go with Mamoswine, you'll have to teach it Ancientpower via move tutor in Blackthorn so it can evolve. Since the tutor requires one Heart Scale, you may have to smash some rocks in Cianwood to get one, or, there's a hidden one in Route 42 (search with dowsing machine).

Keep Ampharos and Vaporeon.

For the last slots I'd go with Vulpix and Umbreon. However, be warned that Vulpix won't do much until it evolves. I talk from experience as the first (and only) time I played through Gold I used a Weepinbell and back then the only way you could get the stones was from Bill's grandpa in Cerulean and I was stuck with Weepinbell for ages. You can also dump Vulpix for a Ground-type like I said.

Dragonair should do well against the E4 but it doesn't have good stats. When you evolve it, though, you'll have a powerhouse on your hands.