#zygor

My guess is that the three of them met at Duelist Kingdom when Bandit Keith brought them together. However, I like to think they could've been friends before that. After all, there's so little information about them that we practically are forced to make up headcanons.

In the manga, that's the only time they appear. They weren't with Kotsuzuka during his Duel against Yami Bakura.

I'm glad they did stay together in the anime. Unlike when they followed Bandit Keith's orders, Kotsuzuka's gang seems to have no leader. They treat one another as equals, so much so that they were okay with working together to get at least one of them to the Battle City finals. It would mean achieving what they couldn't at Duelist Kingdom because of Keith. I see them as close friends.

The red-haired one is Kiyoshi Takaido, or Sid in the dub. His full Japanese name is shown in the episode where we see their rarest cards.

Takaido seems like the kind of friend who backs you up from afar. He doesn't talk much compared to the others. However, he can have an explosive personality, and has no problem with provoking others. He can be a bit of a coward, too. We didn't get to see enough of him. I think his character holds great potential to explore in terms of trust, bonds, and self-improvement.

His rarest card being Firewing Pegasus, along with his hair being red and shaped like a flame, has led many of us to assume that he could be a Pyro/FIRE duelist.

The black-haired one is Satake, or Zygor in the dub.

The scene I mentioned earlier doesn't last long enough to show his first name. However, he may actually have one. I plan to make a post specifically about this in the future.

Satake seems to have experience fighting, so I wonder if he tends to get into fights often or what kind of past he carries. He's shown to be very supportive of Kotsuzuka. I like to see him as the protective one, and the one who keeps the group together.

Due to his rarest card being Twin-Headed Thunder Dragon, and the shape of his hair, many of us assume he plays a Thunder Dragon deck, or specializes in Thunder monsters.

I doubt they have canon ages. We are lucky they even have names in the anime, since they were nameless characters in the manga. They could be 20, or they could be 17. Who knows? I guess we'll have to resort to headcanons, much to my disliking.

With Yugioh, there's no way to tell a character's age based on their appearance alone. Tell me about it. I frown every time I see someone assume Kotsuzuka is 10 or something just because he's short. Sometimes I want to yell 'Kotsuzuka is 15, people, fifteen!!!' at them. He's only 1 or 2 years younger than Yugi's group.

This is one of the reasons why I like to imagine Kotsuzuka, Takaido and Satake as childhood friends. If that's not the case, meeting for the first time at Duelist Kingdom, getting along, and then bonding after Keith's betrayal (like you said) also works.