The Battle Center's your best bet for battles, from entering tournaments to having your teams rated, so I'm glad to see you've already posted there! Wish I could help you out a bit, but sadly I'm not yet a good enough competitive battler. Maybe someday, haha. Anyway, welcome to PC, Gyarados! :D
Outside the Battle Center, you can also ask about EV help over at the
4th Gen Help Thread since you're planning on EVing in your SoulSilver. The regulars there would love to help you out! The 4th Gen section is a pretty great place on the forum overall though and has some really interesting topics for you to discuss, so hopefully you explore around there a bit more if you're interested. Have you tried the newer games yet, like Black 2 or White 2, or are you mostly sticking to the 4th gen for now? I loved HG/SS and am kind of wanting to restart mine, since I moved all my important Pokemon over to White anyway.
Anyway, that's all from me, so have fun here on this wonderful forum and I'll see you around! Make sure to give the rules a read so you understand how things work here (if you haven't already) and enjoy your stay. <3 If you ever need help, I'm always open to assist you, so feel free to leave a message anytime!