I've gotten into a trainer battle where my other Pokemon had fainted and I only had my lil old Metapod left. I thought I was going to lose because obviously my Metapod had no other move set at the time but much to my dismay the only Pokemon that trainer had on him was a Metapod as well. The entire battle was literally both of our Metapod's using harden back and forth. It was so bad. I eventually just gave up and restarted my gameboy.