Would OP please type properly. There is no need to type the way you are and it is really hard to read. Thank you.
From watching the few episodes Takuto's been in it seems that he isn't the evil character he is made out to be. He didn't flip out after his "unbeatable" Darkrai got beaten and even had the courtesy to say something to Ash after the battle(I'm not sure what was being said, I don't know Japanese).
At the end ceremony he was cheering and looked happy. I think he is a misunderstood and extremely shy. He might have been bullied or put down as a child and sought power as an adult as a way to show his bullies that he wasn't the weakling they thought he was.
Takuto had a major drive unlike any other human being. Darkrai noticed this and felt sorry for the man, he was only trying to live out his childhood dreams and prove his bullys wrong. Takuto has to be a nice person, if you get picked on then you have to be nice otherwise no one will like you, same with fat people. If you have a fat person that is a complete arse then they will struggle to have any friends.
From this we can see that Darkrai, who most likely suffered the same issues as Takuto, decided to tag along with Takuto and defeat the Sinnoh League singlehandedly, to show that they are strong and powerful, proving their bullies wrong.
Then, moving on to other legendaries.
As I said previously Takuto has to be a nice person, anyone know Sigmund Freud. Well, Takuto would be the super ego, the person who would sacrifice everything for the sake of someone else. He won Latios over with friendship, and Latios also felt sorry for Takuto so tagged along with him also.