How many EV's can you have for each stat?
If you train your pokemon (1 EV in Attack) against a pokemon with 1 EV in Defense, does your EV's on your Attack stat go away?
How can you see all EV's your pokemon has gained without an Action Replay? 5
1. You can have 255 EVs for each stat, and you can have 510 in total.
2. No, you still gain that EV.
3. Unless it's on PO or another Pokemon Simulator, you have to keep track.
Hope This Helped :D