Meganium
The Herb Pokemon evolves from Bayleef at level 32.
In order to obtain a bayleef, you must raise a chikorita to level 16.
Chikorita is obtained in Emerald from prof. Birch after completing the Hoenn Dex, or from Pokemon XD, which is a gift from defeating Mt. Battle. This chikorita comes with Frenzy Plant.
Ability: Overgrow: Grass type moves become 1.5x their normal amount under
Base Stats:
Hp: 80
Atk: 82
Def: 100
Sp. Atk: 83
Sp. Def: 100
Speed: 80

Weaknesses: Fire / Ice / Poison / Flying / Bug
Resistances: Water / Electric / Grass / Ground

Move Set #1:
252 hp 128 def 128 sp. atk
Bold
Lefties
Aromatherapy
Energy Ball
Synthesis
Leech Seed
UU cleric - This set allows you to pull off aromatherapy, and not be blissey. Meganium has okay attacking stats, and so can pull off using attack to some avail Synthesis is a good one turn recovery move. Leech Seed allows more hp to be siphoned off to make up for meganiums less than amazing sp. attack stat.
Move Set #2:
216 hp 128 sp. def 128 sp atk 40 def
Calm
Lefties
Counter
Reflect/Light Screen
Synthesis
Energy Ball
This attempts to lure in physical attackers, or to trap them. Counter is a way to hit them where it hurts. Reflect ensures that you live from there, but light screen draws in the physical attacker. Synthesis for recovery, and Energy Ball for attacking.
Move Set #3
252 hp 128 def 128 sp. def
Bold
Lefties
Grass whistle
Sub
Toxic
Leech Seed
Double Powder Attrition Destruction, or Dpad. While it doesn't have two powders, it has similar versions of both. Grasswhistle puts them to sleep, then you can toxic whatever may switch in. Substitute increases your chances of pulling off more status, and leech seed plus lefties to give you more hp.
Move Set #4
252 sp. atk 252 speed
Timid
Heat Rock
Ancient Power
Solar Beam
Synthesis
Sunny day
This is a special sweeping set with Sunny Day to help set up Solar beam as well as any other sunny day team pokemon you may have with you. Ancient Power to catch the flying-type trying to get you off guard. Synthesis in Sun is really handy. Solar beam
Move Set #5
252 speed 252 atk
Jolly
Kings Rock/Lefties/Life Orb
EQ
Body Slam
Synthesis
Rock Smash
Attacking Set. Body Slam paralyzes, EQ waxes fire-types,synthesis for recovery, Rock Smash for incoming ice types as well as lowering the defense of your opponents.
Move Set #6
216 hp 128 def 124 sp. def 40 sp. atk
Bold/Calm
Lum Berry/Lefties
Energy Ball
Safeguard/Aromatherapy
Toxic
Synthesis
Similar to the first set, but with Toxic and aims at attrition more than support. Safeguard or Aromatherapy is a matter of preference.



Thanks to babel for inadvertently helping me with the organization of my write-ups!