Candy/Dust Bug

I remember someone mentioning previously that catching a Gyarados will only produce 3 candies and 100 stardust even though it should give 5 candies and 300 stardust since it's a stage 2 Pokémon. I haven't had the opportunity to see that myself since I haven't caught a Gyarados recently.

But, I was at an Electabuzz nest last night and I just realized that it only gives 3 candies and 100 stardust even though there's Elekid! Has anyone realized that?

So if I catch a Pikachu, does it give me 3 candies/100 stardust or 5/300? Since there's Pichu, it would make sense for the 5/300 right?

Or are all the "babies" like Pichu, Cleffa, Igglybuff, Smoochum, Elekid, Magby, Tyrogue and Togepi don't factor in for the supposed increase in candies/stardust?

But I do remember catching a Togetic that gave me 5 candies/300 stardust.... what's the rule here?