Its level 100 without any EV train and it's HP is 338.I haven't EV train it.What's wrong ?
Techinically, whenever you battle, you EV train, just not to one stat. You earn EVs every time you battle. The minimum is 300 with no IVs, 331 with IVs. So you must have gotten 28-31 HP EVs.
Nothing its Ivs probably put it to that much the lowest it can have at level 100 is around 300.