Bronze can be achieved solo on the Speed Run of Entrance A on level 1-1 Woodland Vestibule without any gadgets equipped. This requires a bit of luck and some skill. I have included a video of my Bronze run on this level with no gadgets used. This is my video, of me playing, captured on my Xbox One Game DVR and uploaded onto my YouTube Channel. You'll notice in the video that I rode the Chariot over the gap after going down the big hill. If you jump down the gap and pull the Chariot down behind you, it saves a couple seconds. I did a Silver and Gold run as well, available on my YouTube channel, but those two required a gadget.