Er... uh. I'm so rusty with forums I'm actually kind of nervous. <_<;
Name: Pat
Partner Pokemon: Nidorina (the Nidorina. No, I'm not being facetious, that's her name)
Topic: I'll do you a couple at once... If I may combine Who's the Cutest Poison Type from way back with Favorite and Unique.
The answer to both is either Nidorina, or the first answer may be slightly skewed towards Nidoran Female, it literally varies daily. But I'm crazy about Nidos. Kind of. Okay, not as much as I used to be, but still enough to be consistent. To be honest, I really only like Nidoran F through Nidorino, I've never really felt anything for Nidoking (though I like some interpretations I've drawn).
Overall, though, Nidorina has been a top favorite for about 12 years, only being edged out length-of-time wise by Vulpix (my first favorite, who dropped to rank two/three as soon as I started loving 'Rina more). I'm also going to level with you all, I haven't touched a major Pokemon game in what feels like forever (the last side game I played was Rumble on the Wii, though). So the reasons why I think Nidorina is unique will have nothing to do with game stats, but more aesthetics of her design.
I feel like Nidorina has all the features that give her an appeal of a classic (pocket) monster, but at the same time, has a very strong silhouette that allows for a lot of creative interpretation just as long as you get the core elements down. That's strong design, I think. It's also why a Pokemon like Voltorb is unmemorable. She's not too over done like some of the other Nidos, but not too uninspired that she looks like Kirby with hair (you know who I mean), and the details are easy to remember. Almost everything is in threes. Three ear points, three claws, three toes (the middle one being larger). She doesn't have an insane amount of spikes to keep track of. Just four, and they sit on her back 2 by 2. Easy, easy, easy, and yet you'll never mistake Nidorina for another creature if you have any familiarity with her.
She can be charming too, depending on which art you're looking at. The anime did a horrible job of representing her, because it erroneously based her design from the Red/Green sprites, as opposed to the calm look she had in her old Sugimori promo art. Unfortunately, everyone remembered her for her anime design, but I think people have gotten away from that these days (I'd like to think I had a hand in that :D;).
I've drawn Nidorina so much in the past decade and two years that it's second nature, and I've really come to appreciate that solid, solid design. THAT'S why I think Nidorina is unique.
Game wise, Nidorina holds a special place thanks to Pokemon Silver, a game I didn't even like (so you know there had to be another draw). But that's a story for some other time.
As for fan art... uh. I'm not sure if I ought to. Oh no, it's nothing bad (I'm a very family friendly, cartoon loving kind of guy), but I still can't help but feel it'd be somewhat self serving. :Y I'm always apprehensive about these things.
I also never know how to feel about posting found art. Like, I technically don't want to because I have too much respect for the artists who don't want it redistributed (and I've been there in the past, don't care anymore these days), and yet... well, here's one of my old favorites. It's not mind blowing coloring wise, but I always thought it was amazing by the sheer fact that it came from a Japanese oekaki. Japan. A place where they go out of their way NOT to draw Nidos (I'm exaggerating, but still). And not only that, the art doesn't look like it came from a guidebook. It's full of so much character (it reminds me of the Yamashi-ta 4Koma (yikes, I understand the need for a filter, but it's the dude's name))! Truly a gem on those merits alone!
So, yeah. :D