As motivation to make another page at last, I have decided to incorporate Hikaru no Go into it. Hurrah!!
First, here's a summary for both series. BOTH of them, that's right!!
Boy finds old antique in grandfather's posession. Spirit that lives in antique takes residence in boy's mind. Boy becomes one of the best players of his appointed game EVAH. EVAH, I SAY!!!!
Okay. Now for comparing CHARACTERS!!! HOORAH!!!
MUTOU YUUGI vs SHINDO HIKARU 
When I first started reading HikaGo, my impression was that Hikaru was a lot like Yuugi - and several people have told me the same. It's understandable, what with the ancient game-playing spirit living in their mind, blonde bangs, and becoming the shiznitz in the game they play. As well as the female childhood friend who is voiced by Kakazu Yumi and the whole finding-an-object-in-Jii-chan's-attic/closet/whatever-and-an-ancient-spirit-comes-out thing. In terms of personality, though... they're complete opposites. Yuugi is timid, quiet, and polite, and Hikaru is outgoing, loud, and rude. :D
MUTOU YUUGI vs KOIKE HITOSHI 
Well, I decided that I should find someone that's like Yuugi in terms of personality, so I instantly thought of Koike-kun. Not only is Koike-kun timid like Yuugi, but he's ALSO short!! And he has funny ears, but that has nothing to do with anything.
But, to be frank, Koike-kun sucks at Go...
YAMI YUUGI vs FUJIWARA NO SAI 
They're game-playing spirits from long long ago!! Except Yami is from Egypt 3000 years ago... and Sai is from Japan 1000 years ago... ant their personalities are so different it's not even funny.
But, frankly... NO ONE in Hikaru no Go has a personality like Yami's. Not even Touya Meijin.
MAZAKI ANZU vs FUJISAKI AKARI 
They're the main character's friend from childhood! And they're voiced by Kakazu Yumi (Anzu was in the first anime, at least)!! AND they start playing the game that the main character plays because the main character plays that game!!!! But they're usually cheerleaders for the better players because they can't compare!! OH, HURRAH!!!
MAZAKI ANZU vs NASE ASUMI
Okay, these two are like duplicates of each other. Seriously. I'm not even going to explain Nase's personality or role in the manga, because it's exactly the same as Anzu's. Except for the fact that Nase's pretty darn good at Go and Anzu really isn't THAT great at Duel Monsters...
KAIBA SETO vs TOUYA AKIRA 
The main character's RIVAL!!! And they're SO determined to be better than the main character!! Except Akira really IS better than Hikaru but Seto isn't better than Yuugi, hahaha. Okay, actually, Akira and Hikaru are equal in their ability to read ahead, but Akira has more strength than Hikaru does, as a result of playing the game ten years longer than Hikaru has... oh, wait, Yu-Gi-Oh! site. Ummm, Seto and Akira aren't really too much alike, really, because Akira has random moments of cheerfulness or self-doubt and those are things that you NEVER see from Seto EVER. And while Yuugi doesn't seem to think about Kaiba EVER, even though Kaiba is obsessed with beating him, Hikaru and Akira are ALWAYS THINKING ABOUT EACH OTHER ALWAYS AND NEVER OF ANYTHING ELSE EXCEPT FOR MAYBE GO OR SAI BUT THAT ALWAYS LEADS TO THINKING OF EACH OTHER!!!!!!!!! HOOOOOOOOORRRRRRRRRAAAAAAAAAAAYYYYYYYYYY!!!!!!!!!!!!!!!!!!!
And Seto has had green hair AND brown hair in the anime, whereas Akira's anime hair is a mix of green and brown YAY!!!
JOUNOUCHI KATSUYA vs WAYA YOSHITAKA 
Duuuuuuuuuuuuuuude......... they're like...... duuuuuuuuuuude...........
*snaps out of random trance* Um, okay. They're both like "MWAHAHAHAHA DUDE MAN I ROXXORZ AND FOOD IS GOOD!!!!"
Um... except not really...
HONDA HIROTO and HONDA TOSHINORI
They're both named Honda and they pretty much have the same personality and role!!!
Or, actually... they have pretty different personalities, but still...
HONDA HIROTO and ISUMI SHINICHIRO 
Okay... they're really nothing alike but I had to put Isumi in here somewhere, okay?
BAKURA RYOU and FUKKUN
Well, I forgot Fukui's given name, so you're going to have to deal with my nickname for him for now. :3 Okay, these two are both like really really optomistic and cute and they couldn't give a flying waffle whether they won or not!!
Uhhh.... that's it for now. I'll add more if I can think of more. *falls over*