Here's my idea.
Give the regional Bug decent stats. Then, give it the gimmick that it pulls in portions of its surrounding area into its cocoon when it evolves.
Next, add a ton of areas into the region in order for there to be a variety of places for it to evolve.
That will give us this scenario. Evolve it in the following places and get the following type combo:
In the grass - Bug/Grass
In a building - Bug/Steel
In a cave - Bug/Rock
In a desert - Bug/Ground
Surfing the ocean - Bug/Water
In the mountains - Bug/Ice
By the volcano - Bug/Fire
Give each forme a somewhat unique appearance to go with their type and the fact they took in certain things to evolve (seaweed, coal, grass, etc.) and boom. We have our Bug type combinations all in one awesome package.
