I understood, it is a pity that it is not possible to know his nature using only his stats, I tried to do some calculations using the basic statistics of the level 64 sceptile in the third generation, and I thought his speed was very low, seeing his other stats, I think he it should be brave, sassy or some neutral nature, but still, as you said, it is a random guess (or at least almost random in this case).
Thanks for the help anyway.
And also thank you very much for the sceptile you created, although it is not the same thing, it means a lot to me to have another skeptical that at least imitates my original.