>>32584638When you get Vulpix, it will be level 18. The problem is that the lower the level, the harder it will be to tell. Therefore, it's best to level it up via Rare Candy. I know its still possible to glitch items in Yellow, but its more convoluted and I don't know the whole process. The required DVs are as follows:
HP: 0, 4
Attack: 10
Defense: 2, 3, 6, 7, 10, 11, 14, 15
Special: 10
Speed: 10
Now for a level 18 Vulpix, see pic related. Notice how the stats are similar? You won't be able to truly tell its DV value. At a higher level however (I chose 50, also included), you can see its easier to tell the stats, and therefore DVs, apart.
In this case, I'll just tell you what stats to look for:
HP: 98, 102
Attack: 56
Defense: 47, 48, 51, 52, 55, 56, 59, 60
Special: 65, 80 (Either SpA or SpD, not sure which was which for Vulpix in Gen 1, but it's one of these)
Speed: 80
If the HP value isn't correct when you first go to check it, restart and try again. Sorry for the long wait.