Almost all Mario players have heard of Goombas. They are those little, angry, buck toothed, brown mushroom thingies.

No - one actually knows if the Goombas are on Bowser's side or not. They just walk around on the platform, minding their own buisness. Goombas  don't intend to harm you they just hurt you when you touch them. Kind of like a jellyfish and pufferfish. It's Mario's fault that he touches them. Instead of doing the right thing and just jumping over them, he insists on jumping on them and killing them. Oh Mario!