You'll be in the Safari Zone a long time :(
Chanseys are extremely rare and there is no Easy Way
Don't bother with throwing rocks and stuff. Just go at them with Safari Balls Any chansey you catch is rare. Just hope that the RNG is kind on you and hope to get a Chansey with a Lucky Egg
In area 1 Chanseys have a 1% chance in appearing D:
Plus only 5 % Chance of holding a Lucky Egg.
The chance of catching a Chansey is roughly 6%.
Therefore, the chance of you getting a Lucky Egg on any specific encounter is:
0.1x .05 x .06 =0.03=0.3 % Chance
You only have a 0.3% chance of getting a Chansey with a Lucky Egg D:
In Area 3 Chansey has a 4% Chance in appearing
Again, only 5% of holding a Lucky Egg.
04 x .05 x .06 =0.12=1.2 % Chance
You only have a 1.2% chance of getting a Chansey holding a Lucky Egg D: