Heres a feel that happened to me directly in PokeMMO
It was just after I started playing the game, there were a few new players around, and we were only able to get up to Cerulean City, my Wartortle had just reached level 22 and I was looking for someone to battle at the Cerulean pokecenter. Then this one guy challenged me, I was ready to go with a 22 Wartortle and a 18 Kadabra who only knew teleport. The battle began and he had pretty standard low level pokemon, lead with a Paras, then Geodude, then an Abra, my Wartortle took them out with ease but then my worst fears happened, he threw out an Ivysaur level 21.
I thought it was over for me, there is no way my Wartortle could take him out but I tried anyway, I use bite and do about 1/4th of his health, then his Ivysaur used Razor Leaf and my fear happened - Critical Hit. But my Wartortle survived with 1 hp! So I contiuned on throwing out another bite, he is a little below half when here it comes... Another Razor Leaf to end me, but it missed, I had another chance. So I gave him another bite and his Ivysaur was now down to around 30% hp, but how could I survive another Razor Leaf? Then my luck turned on, he got Flinched! Used bite again and he was down to one hit, I was extremely disappointed but wait, ANOTHER FLINCH, three turns in a row my Wartortle was spared and I ended the battle with a final bite, leaving me the victor. Since then I have vowed never to take my now level 100 Blastoise off of my team.
tfw I could have told this story in 2 sentences but decided to write 2 paragraphs.