Breed a gloom or vileplume and once you hatch the egg you will receive a level 5 oddish.
you can only get a level 5 or lower oddish by breeding an oddish with another oddish with the opposite genders.
I'm guessing around 14 or 13
Oddish evolves at level 21 + it evolves into vileplume once you give it a Leaf stone.
level 5
oddish eveloves at level 26 into gloom dbzpokeyu
Oddish evolves at level 21 in HeartGold.
Oddish evolves into Gloom at level 21.
level 31
my oddish evolved at level 21 maybe around the 20s
Level 21.
Oddish learns Sweet Scent at Level 7 in Pokémon Ruby.
You have a level 47 Oddish. That's about it. I caught a level 48 Tentacool in my Red Version.