I can tell you! I used to live in Asia and Europe and frequently attended baseball and soccer games.

In most cases, these teams are so old that only a few older original supporters know the “origins”, but people usually go to games anticipating participating, singing and chanting.

In soccer, it’s 100% organic and a 100% fan-produced atmosphere. No jumbotrons, no scoreboard, no cheerleaders. There are usually ultras or supporter groups made up by like-minded fans that want to stand and actively sing for their clubs. Depending on where you are, they’re basically like fraternities. So imagine a college fraternity solely dedicated to cheering with anywhere from 1,000 to 10,000+ members. They have meetings, they hangout together, they drink together, and they make flags and tifos together. That’s when they hash out the songs and chants. They also show up hours before game days and occupy the standing section behind the goal to set up and, sometimes teach new comers their chants. So yes, it is very much like college traditions. If they like the chants and standing up, they stay; if they don’t, they usually sit elsewhere (not where the standing section is). Some are hardcore and show up every game to lead chants as capos, some are more casual. Either way, it snowballs! Take my American hometown Portland for example. The supporter’s group (Timbers Army) started with 20 gus in 2001 passing out flyers and chant sheets. Now they have 6,000+ who show up at least 3 hours early every game just to cheer the team on during warm ups. Here’s an example. You can see the rest of the stadium is practically empty.

Asian baseball is a different beast. While fan participation far surpasses what you typically see in MLB, my time at Taiwan tells me that the team writes the chants, and uses jumbotrons to lead the crowd alongside cheerleaders. Although fans can bring their own material to cheer the team on (I used to bring air horns), the team usually provides for the attendees. The team also hires cheerleaders to lead chants through a PA system, play trumpets, play drums, and wave flags to raise morale. The methods are similar to your typical MLB or NBA game, but the fans participate wayyyyy more than Americans do. These chants are simple and repetitive, so it is very simple to catch on on the spot. Here an example of a male cheerleader telling fans what to do in a game. This is my local team when I lived in Taiwan. It’s also the reason why most youth western national baseball teams get destroyed when they play in Asia. The atmosphere is basically the same for youth teams as well.