In pokemon black and white, I was breeding some eggs and since I didn't have access to GTS, I was figuring out their IVs through giving them half a high level audino's EXP on the route above undella town so I could use online calculators at a more accurate level (this usually got them to level 16.) I had four level 1 houndour and only my sawk and archeops from my team. Things were going fine until I wandered a little too far. Turns out there was a trainer I had avoided the first time I came through the route. Oops, I got into a battle.
My sawk and archeops actually handeled the first two pokemon no prob, but then the trainer sent out her last pokemon, a level 68 espeon. It beat both the fighting type and glass cannon in a single hit each. It was at full health and I despaired as I had to go through the pointless process of picking which level one freshly hatched houndour to get curb stomped by the level 68 pokemon. I picked a little female pup and sent her out, picking ember because not that it would matter anyways. What happened next I didn't expect.
The espeon used Last Resort, which, of course, did nothing as it still had other moves.
For a moment I was confused, why had it used that of all things? And then, it dawned on me. It had no other non-psychic type damaging moves. Houndour was half dark and immune to its phsycic move, so the AI was trying to use Last Resort which quickly ran out of pp leaving it with nothing that could hurt my level 1 pokemon.
The very first ember the little houndour sent out caused a burn to the espeon. I got to watch the miracle of a level 68 slowly burn to death under the hands of the houndour. She ended up taking down the espeon dead alone. The exp bar went up and up and up. Level after level passed.
She gained enough exp to deposit her neatly at level 24. Which also happened to be EXACTLY enough levels for her to evolve into a houndoom. The badass houndoom earns herself the name The Major and a place on my team. Turns out her IVs were "Outstanding" too. **** yeah it was the best thing ever.
tldr; Level one, freshly hatched houndour finds itself stranded in a battle with a level 68 espeon. She manages to beat it, gains 23 levels all at once, and evolves all in one fell swoop. She's a badass and named The Major.