X-Men: Have Yourself a Morlock Little X-mas (1995)
Jubilee is excited about her first Christmas as an X-Man. But when she is out shopping with Wolverine and Storm, they run into some Morlocks stealing medical supplies. They learn that Leech is sick, and the Morlocks resent that Storm (their putative leader) hasn't been there for them. So they go to try to help, and possibly hope for a Christmas miracle.
Overall it's a cute episode. It's fairly well written, though some of the jokes fall flat. I couldn't resist the silliness of Jean Grey and Gambit fighting over holiday cooking, although I would completely understand someone cringing at those scenes.
The animation is oddly static in places compared to what is commonly done now, particularly in characters' faces. It wasn't too distracting, but it is sometimes hard to see much emotion.
Yes, there are some very dorky moments, and the whole ending is pretty over-the-top sentimental, but I enjoyed it. It's a kind of holiday sappy that I am occasionally okay with. Erin didn't like the sappy ending, but he doesn't have as many old memories of this series as I do. This is the show that really hooked me on superheroes, even before Batman:TAS.
Should you see it? Sure. It's cute, and very seasonally cheerful, without being too forced. It made me smile. Be aware: normally I would choke on this level of sentimentality, and I think Erin did, so your mileage may vary.
I had this episode on an ancient VHS tape, but you might be able to find it on YouTube, or it's available on Volume Four of the DVD sets.