Ground

Now I'm really proud of this one, I've noticed that Megaman and Bass have the best robot master designs: that's because they were drawn by professional manga artists rather than made from childrens' concepts.

Groundman was fun to draw because he transforms into tank mode, which is what the left side of his body is doing. Steelix works because of the giant drill attack Groundman uses reminds me of Steelix

Groundman (Capcom)
Steelix (Gamefreak)