You had caught a Dragonair a while back and trained it very well. Fast forward a bit and...Dragonair evolved into...Dragonite!

Suddenly your Dragonite flopped onto the floor with a loud SMACK! before he started speaking

Dragonite: I slithered my entire life. You think I can just suddenly start walking? he said with an almost smug look on his face as he lay there looking up at you