I must say, I'm actually quite impressed that you get that much story out of that little space. That's not always a good thing, but I feel like it works here. Although, I do have a couple suggestions.
...on the sea alone separated from its...
You need a comma between "alone" and "separated" since they're two different ideas. In the first half, you're focusing on the Tentacool itself, while on the second half you're focusing on its family and friends. So, I would separate the two with a comma.
...winter comes and tentacools body...
Same thing here between "comes" and "and". "And" in this case is a transitional phrase, which need commas before it.
As a articuno flys over it glooms down realising tentacool is near death,
Since Articuno starts with a vowel, you would use "an" before it instead of an "a". I don't think the Articuno is "glooming" down. Perhaps you meant something like "gazes"? Lastly, you misspelled "realising". It's spelt with a "z" instead of an "s", like so: "realizing".
...tentacool had died...because of its sheer presence.
You need a space after the ellipses (...).
You're telling us the story, rather than showing. Since I work best with example, here's what I mean:
soon winter comes and tentacools body begins to freeze.
Don't tell us poor Tentacool is freezing, show us. Does the water surrounding Tentacool start to freeze? How does the Tentacool itself start freezing? Asking simple questions like that can help with showing. It describes the event to the reader so that instead of listening to the story, they're actually there. They feel the cold water freezing around them. The reader sympathizes with the dying Tentacool. It's a whole cycle that starts with showing. It's an incredibly hard skill to pick up, but improves your writing immensely.
As the wind blows his flame slowly disappears all whilst the frost let off by a passing by articuno sits on his head,
I felt like you tried too hard to fit too much into this line. I would separate out these lines if it means you're not cramming the details into a small phrase. It ruins the flow, confuses the reader, and is just bad for your story in general.
Overall, I like it. These are two short (really short) stories that actually have a lot in them. Normally I would tell you to expand on the ideas, but the stories actually make sense being this short, so you're good. Plus, the short length makes the stories incredibly inviting to read. Not bad and I do hope you'll make more of these.