This is my example of how it should be imo, that I posten in the update thread:
Dratini 1 CP: 100 IV: 100
Dratini 2 CP: 200 IV: 80
Dratini 3 CP: 300 IV: 60
Dratini 4 CP: 400 IV: 40
Dratini 5 CP: 500 IV: 20
So which is the best you think? Imo none is good.
Why? Dratini 1 will take you enormous amount of stardust to power up which is just not worth it.
High CP and low IV is also useless.
Lets say you now have:
Dratini 1 CP: 100 IV: 100
Dratini 2 CP: 200 IV: 80
Dratini 3 CP: 300 IV: 60
You now catch:
Dratini New: CP: 400 IV: 80, what should it replace?
Imo it should replace Dratini 3.
You now have:
Dratini 1 CP: 100 IV: 100
Dratini 2 CP: 200 IV: 80
Dratini 3 CP: 400 IV: 80
You then catch:
Dratini New 2: CP: 300 IV: 90, what should it replace?
Imo it should replace Dratini 2.
You now have:
Dratini 1 CP: 100 IV: 100
Dratini 2 CP: 300 IV: 90
Dratini 3 CP: 400 IV: 80
You then catch:
Dratini New 3: CP: 200 IV: 95, what should it replace?
Imo it should replace Dratini 1.
You now have:
Dratini 1 CP: 200 IV: 95
Dratini 2 CP: 300 IV: 90
Dratini 3 CP: 400 IV: 80