>>15101637> It was a 3-stage pokemon to which they added a "baby" formThat hasn't happened ever.
Past two gens have had zero babies.
Gen 4 added Mime Jr, Bonsly, Budew, Chingling, Munchlax, Happiny, and Mantyke. All of which were 1-stage Pokemon except for Chansey, who was only two stage. Budew was added with Roselia, giving it 3 stages, but still not 4.
Gen 3 only added Azurill and Wynaut. Neither of which have 4 stages three generations later.
None of the Gen 2 added babies were to any Pokemon with 3 stages already because there were only like 10 Pokemon with three stages anyway back then.
You're either taking pre-gen speculation you had to heart or you dreamt it, either way, you're wrong.