Hey there Jin, welcome to PC and it's good to meet you! Will start off by saying thanks for writing a more thought-out intro, it really helps me (and others) make a better reply in your thread! <3
Pokemon Netbattle.. that rings a bell even though I wasn't much of a competitive battler that long ago. You definitely did have quite an extensive battling history - getting involved in these little communities related to your interests helps you make a lot of friends you wouldn't have met otherwise, so those experiences should always be considered pretty special. But enough of the cheesiness or I'll put you to sleep! Our regulars already linked you to our Battle Center section for your battle-related needs, though our official battle server is on Pokemon Showdown rather than Pokemon Online. Have you ever tried out Showdown yet? It's browser-based (no downloading required) and is a lot more visually appealing, I think, since we get really pretty animations during the battle whereas PO is static from what I remember. A lot of amazing people use the PS server here and it really is one of the friendliest parts of the site so you should get involved and battle our members there sometime. :D Definitely check that out!
And you totally didn't say too much about your battling history as it was rather enjoyable to read. Forums like PC bring all different kinds of fans together and it's wonderful hearing their individual experiences when it comes to Pokemon. <3 I'm a little jealous that you play instruments, are there any particular ones you like to play more than the rest? Piano and violin are some of the most beautiful ones in my eyes and I'd love to own a piano again. Sadly we sold our old one when we moved out of Europe though, ack.
Since you have a lot of interests you'll probably be interested in many places here and hopefully everything is to your liking! Enjoy your stay, read the rules, and see you around~