You can check IV's after defeating Leon in the the Battle Tower. After you do, go to Pokemon box view and use the judge feature by using the + button. If a stat is "best", it is a 31 IV.
If it isn't naturally "best", you can hypertrain a Pokemon to give them a 31 IV stat. If you have bottle caps, you can trade them to a Battle Tower Personnel to give a stat 31 IV. When you do this, the judge feature will tell you "Hypertrained".
To max out EVS, you have 3 options.
- Train them the old fashion way and battle Pokemon that give you EVs of the stat you want until its maxed out.
- Use Vitamins. You can buy them with money in the middle Pokemon center in Wyndon or with BP in Hammerlocke I think. 1 vitamin equals 10 EVs for the stat they're for.
- Pokejobs. Every hour in the stat training Pokejobs give 4 EVs. 24 hours will give you 96 EVs.