GIANT MONARCH BUTTERFREE FAMILY
Species: D. papilio
Subspecies: D. papilio rex
[Some notes first, I want to clear my naming of families. While all Pokémon families in-universe are called by the first stage, e.g. the Charmander family or the Poliwag family, I'll be making an exceptio: the bug families that undergo metamorphic evolution will be known by their adult form, like this one. Now, Butterfree line was a challenging one, not because a variation was hard to design, but because there were so many options to choose from, it was a real deal to select just one. Finally, I chose the one that appeared as the most recognizable to me and thus, we got a Monarch butterfly Pokémon! Please comment your reviews.]
The Giant Monarch Butterfree Family is among the most recent subspecies of Butterfree, which would explain why they are pretty rare in the wild.
There are many factors behind this family getting branched off the Butterfree Family tree, the very first reason being the competition of survival against their common natural rival Beedrill. This family has developed strong Psychic powers to counter the Poison type Beedrill and hence, take dominance over the habitats that both the Pokémon share. Another reason for the variation in the species is the environmental adaptation. While the common Butterfree are naturally forest dwellers, this family is more urban, residing in gardens and small woods.
The psychic abilities in this Pokémon family develop as soon as the offspring is hatched. The Caterpie hatched from the same parent are all psychically connected and are excellent in fending predators off by combining their psychic powers together. Unlike the normal Caterpie, this subspecies do not need to stick itself to a tree in order to form the chrysalis form Metapod. The Monarch Metapod are able to levitate freely in the air thanks to their telekinetic powers and thus, need no support to hang on to. Once the Metapod is mature enough, apparent by the colour change of the chrysalis from bright green to transparent, the Monarch Butterfree breaks free in all its might.
Along with size, the Monarchs are greater than their common counterparts in terms of strength as well. Expert in using their psychic powers to the full, the Monarchs make formidable opponents in battles. They have a higher intelligence than most other Bug types, along with a boosted Special Attack and Speed. The spotted white on black colour palette of this family has also earned it the nickname Giant Star Spot.
It should be bug/poison because monarch butterflies are toxic.
There already are waaaaaayyyyyy more Bug/Poison going around. I'm trying to not do the cliché types (Bug/Poison, Grass/Poison, Normal/Flying, etc) as much as possible.
If Pokemon did a region based on my home country (Canada) and continue having regional forms, then I can imagine this as Butterfree's regional form