its weird, because, then, it as though, the stat exp gained from my blastoise that I trained by defeating pokemon counted as nothing. So,I am still confused... ''
It's not like that.
I'll try to explain it a bit better...
Say a Blastoise has 100 base HP. (random number)
The pokemon can have from 0 to 15 HP DV, meaning it can have anywhere from 0 to 30 extra HP.
On top of this, say it can get a total of another 50 HP from stat exp (i can't remind off my mind).
This means that if your Blastoise right now has 150 HP, this could actually be for example 100 + 0 from DV + 50 from stat exp, or 100 + 30 from DV + 20 from stat exp, or anything in between.
However, a Blastoise that has 0 DV will get at best 150 HP from maxing out its stat exp, meanwhile a Blastoise with 15 DV will get up to 180.
Thus, you can't actually know where your Blastoise DVs are, until you level it to 100 and make it get enough HP stat exp that the stat does not increase anymore, at which point you will be able to calculate what its DVs are based on what max HP it reached.
(Repeat similar for other stats).
In your specific empyrical case, it may just be that your rarecandied Blastoise just happens to have significantly higher DVs than the other one.