By leveling up:
* Tackle: Learned at level 1
* Growl: Learned at level 3
* Poison Powder: Learned at level 6
* Spore: Learned at level 9
* Leech Seed: Learned at level 12
* Stun Spore: Learned at level 15
* Growth: Learned at level 18
* Bullet Seed: Learned at level 21
* Natural Gift: Learned at level 24
* Synthesis: Learned at level 27
* Eerie Impulse: Learned at level 30
* Energy Ball: Learned at level 33
* Magical Leaf: Learned at level 36
* Solarbeam: Learned at level 39
* Ingrain: Learned at level 42
* Giga Drain: Learned at level 45
* Spore: Learned at level 48
* Petal Dance: Learned at level 51
* Seed Bomb: Learned at level 54
By TM/HM:
* Hidden Power: TM28
* Sunny Day: TM30
* Safeguard: TM32
* Light Screen: TM37
* Reflect: TM38
* Will-O-Wisp: TM39
* Facade: TM41
* Rest: TM44
* Attract: TM45
* Thief: TM46
* Aerial Ace: TM48
* Secret Power: TM51
* Frustration: TM49
* Return: TM35
* Strength: HM04
* Cut: HM01
* Flash: HM05
* Rock Smash: HM06
By breeding:
* Spore: From Breloom
* Natural Gift: From Breloom
* Bullet Seed: From Breloom
* Stun Spore: From Breloom
* Leech Seed: From Breloom
* Growth: From Breloom
* Synthesis: From Breloom
* Poison Powder: From Breloom
* Rage Powder: From Breloom
* Magical Leaf: From Breloom
* Energy Ball: From Breloom
* Giga Drain: From Breloom
* Seed Bomb: From Breloom
* Petal Dance: From Breloom
* Ingrain: From Breloom
* Solarbeam: From Breloom
* Eerie Impulse: From Breloom
* Grass Whistle: From Breloom
* Pollen Puff: From Breloom
Please note that some moves require specific conditions to be learned, such as a specific level, a certain held item, or the need to be traded.