First of all, what do you mean by "81% for Intelligence?" Percent means "out of 100" as I'm sure you know. There is no "out of 100" for skill points. Basically you just raise the skill points as much as you want to. The more skill points, the more it helps.
Secondly, your Tamagotchi will graduate from school if your Tamagotchi has been unpaused and awake for 24 hours after it evolves into an adult.
Thirdly, that's all you do at the school. Every time you guess correctly your Tamagotchi gets three skill points (3 Intelligence points if the teacher is Mr. Turtlepedia, 3 Style points if the teacher is Ms. Flower and 3 Kindness points if the teacher is Mr. Canvas). When your Tamagotchi meets a teacher for the FIRST TIME (when you get the [ ! ] mail letting you go to school) you can scroll through the teachers by pressing the A or C buttons. A tip for the school game: When two boxes flash, it means they've switched.
Fourthly, to my knowledge a Tamagotchi cannot be potty trained. Nobody has ever been able to do it before as far as I know.
Fifthly, what do you mean by "5%?" I'm assuming you mean 5 marks on the training bar (though 5% would be less than 0.5 of a mark). The training bar should read "Discipline" for it to make sense, seriously. When your Tamagotchi beeps and has at least one hunger heart full AND one happy heart full and isn't ill, punish it for beeping at you for no reason. When your Tamagotchi cries and has at least one hunger heart full AND one happy heart full, praise it to comfort it. Also, if you have another Tamagotchi of the SAME version, wrap a present and send it over and your Tamagotchi sends something nasty (like poop), it'll sit at the BOTTOM of your screen and grimace. At this time you should punish it.
Sixthly, you should NOT give your Tamagotchi a time out. One of my worst memories is when I was on my 10th Generation and I was raising an Oniontchi named Gotch on my v1 and I wanted my first Mimitchi. Someone wanted to look at my Tamagotchi so I let them. Guess what? They tried to play games, and since they couldn't because my Tamagotchi was at such a low weight, they punished it three times. I was fuming. By the way, I was pretty lucky- I still got my first Mimitchi.
Anyway, a Tamagotchi won't play games if it's too close to its minimum weight. For example, if you have a Tamagotchi that has a minimum weight of 10g, it won't play games until it weighs 13g.
Seventhly, Tamagotchi Town does not have passwords for the tickets. You'll have to search your shop. Be sure to raise a lot of Gotchi Points, as those tickets are REALLY expensive (I seem to recall one being 20 000p). To make the shop restock, set the time to 2.59pm or 6.59pm and wait one minute.
