First, a quick lesson. Galge, the word that looks like it has something to do with mouthwash, is short for "Gal game". Also known as bishoujo game (lit. Pretty girl game) they're like choose-your own adventure books in game form. They typically allow you to date, or end up with a girl by the end of the game. In other words, it's a dating-sim. If you didn't already notice, galge are marketed towards guys. The ones marketed towards girls are called otome games.
To be honest, I've never really played a galge or a true otome game, I think... except for Tokimeki Memorial Girl's Side 1, 2, 3 on the DS. I want Heart no Kuni no Alice, but this is good enough, since I only want the pretty CG graphics. I really haven't gotten them all but... meh. Both Galge and Otome games usually have several types of characters. I'll use TokiMemo: GS... Mostly GS2, since it's my favorite, as examples:
The Osana Najimi/Childhood Friend:
He fell in love with you as a kid and didn't bother asking his parents how to contact you. Instead, he promises that you will meet again someday even though you're probably moving halfway across the globe. About 8-10 years later, he automatically recognizes you at first sight and doesn't bother mentioning this until you've dated for 3 years. At least in TokiMemo: GS3, you actually recognize them right off the bat. They're usually the main "Have-to-get" guy (or girl) in the game.
Saeki Teru, my second goal for GS2, was a pain. It took 3 tries to get his ending. I nearly gave up since it was confusing as I-don't-know-what. You have to be really Smart, Cute, Fashionable, Athletic, and Artistic to get this guy.
I tried doing Hazuki's route, but, I didn't get very far, and for some reason, he rejected me at the end of the game.
Shota are cute, adorable boys who are typically older than they look. That makes this legal. Made to appeal to those girls that adore cute things, at least 90% of the time you'll be saying "AWWW". They're often sugary sweet, or in Amachi's case, only sweet on the outside. Both GS1 and GS2's shota are also your kouhai (underclassmen). Since you're a grade higher than them, they'll both refer to you as senpai.
I especially liked GS2's Amachi Shouta. I swear, that kid looks cute, but he's really a demon... and he uses his cuteness to con people. Overall, it had quite a few good CGs, that showed both sides of his personality. He's my current favorite~
I hated GS1's shota, Hibiya, so he gets no pictures. I tried doing half of his route, but he got kind of annoying after a while. He wants to grow up to be a great man, and makes everyone his role model. For some reason, his love meter wouldn't go down.
The Megane/Glasses Guy:
The (smart) one with glasses. He's... very smart. In GS2, Hikami's the student council president. They aren't really special... Unless you take off their glasses. Then they transform into Bishounen.
I tried avoiding Hikami (top) for the better part of the game. I just
found him terribly annoying. I still got half of his CGs since I had to
be supah-smart to get Saeki. His sleeping CG is pretty nice.
In GS1, I did Moriyama's (bottom) route, he's the sweet, sensitive, smart, fun to pick on guy. His face when you poke/touch him (it's a DS, you know), was amusing. But he got flustered when you touched him too much. It's pretty funny when you go to visit the indoor pool...
Chris is your token foreign guy. I didn't get his route yet, since he's a bit too odd for me.
Mihara is equally odd, but he was the first guy I came across. His route was surprisingly sweet. Though, he could come across as EXTREMELY effeminate. His hair is waist length, he loves the merry-go-round and he declares himself fairy prince and crowns you fairy princess. ...Yeah. He's got some serious moments as well.
The Sensei:Your teacher. There really aren't specifics on this one... Your teacher is always going to be some bishounen that finds it OK to date you, presumably after you graduate.
Somehow in GS2, I got Wakaouji-sensei's (top) confession when I failed to get Saeki. I honestly did not want that at all. But that's how it played out. I still need like... 20 of his CGs, not totally sure when I'll start on that...
In GS1, I totally failed at getting Himuro-sensei (bottom), the cool, but strict homeroom teacher. TOTALLY FAILED. I wasn't smart enough... He's pretty hard to get, since he's slow at raising love points. He's a professional guy. I think he's secretly some kind of ninja or something. He makes a return in GS3, but he's not dateable.
Basically exactly what is says. For some reason, he's unimaginably cool. So cool, you can NEVER reach that level of cool. They're always fashionable (more fashionable than you) and have a ton of fan girls.
The Cool Guy:
GS2's resident cool guy, Hariya (top), is a member of a band. But, he seemed too angsty so I didn't bother going for his route.
GS1's cool guy is a flirtatious, tanned, motorcycle-owning dude. However, he also has hidden angst. I didn't go for his route either. Though, he was one of the first people I met when I randomly raised stats.
The guy who is more athletic than you ever want to be, but not as smart. He skips classes to practice basketball, but doesn't understand the meaning of teamwork. Somehow, through falling in love with you, he learns to stop being a ball hog.
The Sporty Type:
Suzuka required me to be really stupid and take remedial classes every semester, in order to boost my athleticism. Then he got stolen away by
The Pedophile Older Man:
This was just plain creepy. You don't find him, he finds you.... He's one of the secret datable characters in GS1. I don't know what parameters caused me to run into this guy, but I don't want to do it again.
You meet him when he invites you into his
The "Here to Make You Feel Like A Pedo" Character:
I'm not even sure what this is. It's a 12 year old boy...specifically your 12 year-old information broker in GS2. He's not dateable per-se, but he does have a romantic ending. He confesses his love, and mentions that he'll grow up to be a good guy for you. Awww.... How cute.
But wait, how do you get this ending?
You have to use your touchscreen and do skinship lessons every month for 3 years. Skinship is the ability to touch, rub, kiss, etc. your guy to raise love points. Now you have to do this a total of 36 times in the game with your clearly underage neighbor... Upon clicking the Skinship lesson option, he comes into your bedroom and invites you to link arms, give him a peck on the cheek, stare into his eyes ... look at his body...
I felt pretty uncomfortable doing this...
The Quiet Guy:
Is usually a the big, scary looking guy who doesn't say much. When you get to know him, you find out he's actually a huge softie who is afraid of hurting people.
Didn't go for this guy's route either.
There are more characters, but I haven't unlocked them yet, and I'm too lazy to. These aren't all the character types, since a lot of them mix types, I can't find anymore clear cut ones, especially in the case of GS3. Honestly I'm just lazy and GS3 is in Japanese.