lf you mean comparing the two side by side, than yes it would really have to depend on
IVs and EVs, but unless they're exactly the same, the evolved form will have higher stats.
When it evolves, the game calculates its stats based on the evolved Pokemons base stats.
Like how a Charmander's base Attack is 52, and when evolved into a Charmeleon, its Attack
stat will be raised because Charmeleon's base Attack is 64, of course assuming that they both
have the exact same IVs and EVs.
Although there are some exceptions, such as Scyther and Scizor, where when evolved,
Scyther's base Attack goes up from 110 to 130, while Scyther's base Speed goes down
from 105 to 65.
l hope this was clear to you?