Well I maxd out and ev traind allmost all the pokemon I need for my brand new team but the main problem is the levels since I ev'd all of them since their level 1 they rae maxd out on level 13-17 or I don't need to raise anymore of the stats so I don't know how to train them without harming the ev training
Once your pokemon "max out" or gets 510 EVs, it can't get any more. So if your pokemon have 510 EVs training them against other pokemon won't harm your EV training. The only way you can change your EVs now is with EV reducing berries.
Eevee is correct but what would be helpful to you is going to the lady in sunnyshore city/Blackthorn city and she will tell you if your evs are maxed out.