If it's true, I think it's more like gender differences. How many pokémon with gender differences are there?
There could be just a handful of pokémon that show big differences with different parents, notch Ear Pichu being just one. I won't think they'll add more then 50 pokémon with breeding differences, and just a few of those have gender differences too.
Some people say it take to much memory, there are already 8 sprites for each pokémon. But that's not true, there are only 4:
front and front frame 2
back and back frame 2
The shiny sprites are just the normal sprites, but with a different pallet. Not a whole different sprite. Not counting different formes, of course.
One thing that bothers me is that G/S/C show the pokémon in the daycare and if I’m not mistaken you can talk with them. How would they manage this? They can’t possible make 493*3 over worlds for every pokémon + over worlds for different formes. That’s over 1500 over worlds just to make the daycare the same as the original. Of course, back than they were just a few different sprites for all 251 pokémon. Pokémon in the same group shared the same sprite. I don’t think they would do it like this in the remake.