User blog comment:Flippy the french/Why Lumpy appears in almost all the Starring Roles?/@comment-4616886-20130825202445

I think its becuase Lumpy is more flexible than other characters, kinda like Toothy. However Toothy is used more like a place holder. Lumpy's stupidity, mixed with his odd determination and surprising ability to get any job makes him much easier to write episodes for.

To be a little simple, Lumpy has no specific details that make it impssible for certain roles. he kinda fits in a catagory with Toothy, Cro-Marmot and Mole.