this is an "A" grade. It only missed out on the A+ because you didn't include health percentages. Those can be a pain to add, but I find them helpful when reading the warstory.
D+. A 3-0 victory almost certainly doesn't make for a good warstory, and the fact that one of your pokemon didn't even have to come in makes this a poor battle choice.
Also, the turns in which you are trying to fight Jellicent with Scizor are almost upsetting to me. Jellicent is the prime example of annoing burn stall, and a burned Scizor is useless. There was 0% chance he didn't use scald or will-o-wisp in that situation. Since you ended up switching to Celebi anyway, allowing him to burn Scizor was just plain bad.
Also, your opponent not instantly casting a hidden power ice at your Gliscor was very poor strategy. I understand the idea of subbing to scout for the ice fang, but if he didn't think HP ice was a KO, he shouldn't have stayed in.
That's just two examples, but they marked a theme throughout this battle.
C-. Most of your commentary was simply describing your move, which we can get from the battle log. Your grammar was good, which is why this grade is as high as it is.
My advice would be to add more of your thought process, as you did with turn 14, pointing out that stealth rock and leaf storm will more than likely end his Darminitan switch in.
Overall, I think you have the idea of a good warstory down, especially the format. You just need a more attractive battle and some polish on your commentary.