You can find it in two locations:
- Mt. Moon
- The safari zone
Well if you can't find it in the grass try trading with somebody or migrating it but there is probably no other way you can find clefairy in heartgold.
Breed a Clefairy with a Jigglypuff.
In Mt.moon, but be patient, they are not common
nidorino, nidorina, clefairy
nidorina,nidorino,clefairy,and jigglypuff
In saffron city, down and right from the magnet train line. She asks you to find her clefairy doll
Her Clefairy is level 17 and her Milktank is level 19.
Nidorina, Nidorino, Clefairy, Jigglypuff, and Skitty
You have to trade a Clefairy from Leaf Green or Fire Red.
no
it may evolve some of your Pokemon like nidorina to nidoqueen, nidorino to nidoking, clefairy to clefable, and skitty to delcatty
Whitney uses Clefairy and Miltank in Pokémon Gold/Silver/Crystal/HeartGold/SoulSilver and in the anime she has a Nidorina, a Clefairy and a Miltank.