I saw your comment.
23 hp, 12 Atk, 11 Def, 11 Sp. Atk, 11 SDef, 11 Speed
23 hp, 13 Atk, 11 Def, 9 Sp. Atk, 11 SDef, 11 Speed
I think it is just the nature that changed on your tepig.
Hope I helped
Stats are not set permanently at the start of a game. The natures are random. (just a note: Roaming Pokemons' natures are random until you meet them or they begin their roaming)
That's why there is such a thing as "soft resetting". You basically save to re-encounter Pokemon however many times you want until you get the desired Pokemon. Like, with a specific nature in mind, or whether it's shiny or not.
If stats were already set from the beginning of the game, then there would be no such thing as soft resetting.