Yes. It can be still good but just a little difference between stats.
For example if you have a Eevee with a Neutral Nature and Evolve it into Vaporeon, going against a Eevee with a Jolly Nature and Evolve it into a Vaporeon if you look at the Jolly Nature Eevee it's Special Attack it will be about 5-10-15 less then the other one.
If you EV train it enough it should be still Okay in Online Battles, but just a little let back in Special Attack.
Hope this helped. - DragonHaxorus