Uh... EVs are a bit more complex than that.
Each Pokemon has its set level-up stats. By that I mean the stats it will get when it levels up. Those are all set by nature and IVs.
EVs are extra stats, yes, and you can place them wherever you want by EV training, which is battling certain Pokemon to gain certain EVs.
Say I'm training a Mewtwo. What if it's at level one, and I use Rare Candies to get it to 100. There. No EVs. So its stats are lesser.
If I DO Ev train, then its stats are higher.
The max is 252 for each stat. Not 225 ;D
But you're probably saying, YES, GT, that's what I said.
But this is where you went off a bit.
EVs dont necessarily give you one point in each stat for each EV. 4 EVs give you one stat point. If you do 252/4, you'll find that the max you can put in a stat is 63 more stat points.
So EVs just are bonus stats, that you can place by battling certain Pokemon. Every 4 EVs give you one stat point, 252 EVs max per stat, 508 total. You already have base stats, just EVs are extra.