I can understand the thing about the points and all, but, for example, I would need to get mametchi and have a lot of points to get the scientist? Or they turn after teens? Do they have a gender?
Togetchi is not a secret character, he is just a character than can be a obtain in the Meme group with high arts/talent. If you want your tamagotchi to be a scientist make sure it is high in Intellgence (pencil icon) points. No you wouldn't need Mametchi, Mametchi is only a boy on the v4 the female counterpart is Mimitchi look at this chart https://www.tamatalk.com/IB/index.php?showtopic=99281.
Yeah, you MUST have a Mametchi first (for Togetchi), the thing to get it, is that your intelligence points reach 350 minimum and the other two (style and kindness) sum a minimum of 100. When you reach this points, your Mametchi will evolve imediately into a Togetchi. The same goes to Makiko, but first, you MUST have a Memetchi, then do as before only that you need the highest points to be of style. Hope I helped
You don't need a Mametchi to get a Togetchi. It's not possible to get Togetchi from Mametchi. You can only get it from teen characters in the Meme group Gourmetchi and one other. To be a scientist you need to have 50 intelligence points. Other than those two answers I gave you I'm confused about what else you are asking, sorry.
From what I can tell, whenever you get enough points, you turn into the respective special character of that family. So if you are a teen and you somehow manage to get 350 int points and 450 total, you'll get Tensaitchi from a teen. But since you usually only get that kinda points as an adult, it can also be obtained from any adult in the Mame family. I'm not positive about that though, as I haven't gotten any of the special characters yet. (I don't pay enough attention to my v4. >.<
As for your question about the Meme secret character, you can only get her as a girl. If you look at the chart you'll see that the other two special characters can only be males, and the meme family secret character can only be female. Sorry about this.