How to get into "competitive" KH?

Basically I'm playing KH and I'm goin trough the story of the various games n other than the story, I'm noticin I'm loving the gameplay aswell. What are the option when it comes to increasing my level in it? I guess you have the classics any% speedruns or sl1/no damage speedruns, but other than that what are some popular stuff people do to challenge themselves? Are there any begginer guides regardin those?