1 stat point = 4 EVs
510 total (I guess you know all this already, idk)
macho brace = cuts speed, doubles EV gain (pidgey goes from giving 1/4 of a point (1 EV) to 1/2, pokemon who give 1/2 (2 EVs) give a whole point, yadda yadda
you decide how to allocate the points by planning a final movepool for your pokemon, be it phys or special attacks, or improve it's strongest defensive stats. it doesn't always have to be 252 in each, but when it is, there are 4 EVs left over that most people just throw in HP or speed or whatever.
berries get rid of 10 EVs if you screw up, the stat depending on the type of berry.
