>>37261754Rhydon and Rhyhorn don't exactly share any traits other than 'has a horn'.
I believe an interview somewhere might have even hinted at it, but evolution wasn't really a 'thing' until they got the woman on board to design all the cute mons and she went ahead and started making all sorts two stage lines, eventually everyone went back and started designing, for the most part, prevos to Sugimori's early design Kaiju.
It's probable that in an effort to condense all of Sugimori's 'spiky horn monsters' to allow for more variety they decided to merge the two.
>>37261939The morpho would be an early game Bug/Flying shitmon and the compound eyes thing would be the midgame Bug/Poison type with better stats.
Who knows why exactly they decided to switch the designs around, both were made relatively close to each other. I'd speculate someone decided Butterfree's design being cuter was a better fit for early game.
>>37259296Aside from the fact that caterpillars do, in fact, turn into moths, Venomoth isn't actually a moth, it's a butterfly. They're both butterflies.
I know what you're thinking, but a) the Japanese name has nothing to do with moths and b) Names are names, not absolute descriptions, especially in Gen 1. Beedrill is a wasp with spears on it's hands for example. Neither a Bee nor a Drill.