Exactly what did you read about Ninetales's base stats? If you simply looked at the numbers displayed on an online Pokedex page like this one, you've mislead yourself. Those numbers are a factor in determining your Pokemon's actual stat value, but they don't control everything, as there are plenty of other factors such as the Pokemon's level, its IVs, EVs and nature. In fact, if your level 24 Ninetales had stats like those on the Pokedex pages, it would be considered an illegitimate Pokemon as those stats combined are well beyond the possible range for a Pokemon of that level.
According to Pokemon Showdown's teambuilder, your Ninetales' stats are actually perfectly normal, so there is absolutely no issue with your game at all. Its stats are well within the normal range, and while they do suggest that its IVs may perhaps be slightly below average in some areas, its actual stats are not abnormally low. Below is a table that shows the possible range of its stats at level 24 -- do note that it is completely unreasonable to expect maximum numbers in every stat as natures and EVs disallow this, and that to be able to have a maxed stat first place means having maxed IVs in it which is unlikely. Still, as you'll see, every one of your Ninetales's stats are within the normal range.
Stat Low extreme High extreme
HP 69 91
Attack 36 70
Defence 36 69
Special Attack 38 72
Special Defence 53 82
Speed 53 82
Though your Ninetales's stats might seem to be low since they didn't grow much when it evolved, it appears as though they're normal. The perceived lack of significant change it its stats can be explained, in part, by the low level you chose to evolve it at; because the level is low and all other factors are multiplied in some way be the Pokemon's level in the stat formula, there isn't as much opportunity for there to be significant change it its stats. This does not mean that you've made a mistake by evolving it early; a Pokemon that evolved at level 1 will have no different possible stats at level 100 than a Pokemon that evolved at level 99.
Long story short, everything is normal and you have nothing to worry about.