...and we got shiny pichu as well as spiky-eared pichu for HGSS.
As far as I know, the whole pikachu repetition thing is really that a new "Pikachu" species is just created for each generation. Remember when a common name for Marril was Pikablue? I doubt it's just because they are repetitive. There's no other different species of pokemon species that look similar other than the generations of Pika-lookalikes. :3
Pidgey & evos
Tailow & evo
Starly & evos
probably the same thing, a pattern. im just saying that something being reptitive doesnt mean it wont happen.
another less obvious repeat could be Gabite's line and Trapinch's line. ground dragon final evolutions, even though very few people saw a doubling of that type coming. we always have reptilian grass starters, along with bipedal fire starters, with most of the rest of the fires being quadrupeds.
and for an example more akin to the scenario, i would say either Flareon and Vulpix, or Lapras and Gastrodon. similar designs and types, yet both exist. im just saying a repeat doesnt mean it cant happen.