is it good to train your pokemon with it or is it better to battle one on one with your pokemon and will it get the same stats as if it wasnt useing exp.share.
Well I think its better to use EXP. Share because you attach it to a pokmon and even if that pokemon didn't get to be in the battle, that pokemon still gets Experience.
Completely agree. The EVs gained stay the same, and only experience is halved. You can raise two Pokemon at once for about the same amount of time. It really comes down to whether you're raising once Pokemon now for something, or if you don't mind waiting/are raising more than one.
It's only worth using if the Pokemon's too weak to battle for itself. If all your Pokemon are around the same level you might as well train them one at a time, because you get the same experience in the end and there's space for a different hold item.