It all depends on what your IV's are and what you are planning on using on it.
A lot of people will do the standard 252/252/6 but for things like Substitute abuse, you need an exact Stat number.
for exapmle, Choice scarf kyogre vs. choice scarf slaking.
Kyogre, timid, 31 IV speed, 252 speed ev's - 156 total speed
Slaking, jolly, 31 IV speed, 180 speed EV's - 157 total speed
with 180 in speed EV's i can out run a scarf kyogre and i can put the surplus into something else like HP or defenses.
So, like i said - What is the goal of the Weavile?