From what I remember, both trubbish and grimer are a colony of microorganisms coming together to form an entire creature. So considering this, it's possible trubbish is a cousin to the grimer family. If you look at grimer, their body looks fluid or semi solid while trubbish's arms looks kinda like clay. Grimer sometimes produce a rubbery film to somewhat reduce their stench, and Alan Grimes and musk produce crystal structures due to their diets of trash. So it's not out there to assume the trubbish line is just a line of grimer forced to evolve due to the lack of sludge and toxic waste in the Unova region. Thoughts on this?(Yes I know I'm stupid)