I coached my kids a few times over the years when there was no other coach to do it. Never in anything that much resembled competitive leagues of kids/parents with big dreams. Not too much drama involved at that level. I always explained to my son that I didn't coach his teams like other dads because I only know so much about any sport from a coaching perspective, and what I know I'm already telling/teaching him, so a year of me coaching him is a year he's not really learning anything new.
That said, one of his last years in sports I coached his basketball team in a church league at some random megachurch that had basketball for one year later than most other youth sports, I think it was 11/12 year olds. Where I am, it's tough to find sports leagues for middle school aged kids, you either make your middle school team or you're pretty much done. But this one mega church had basketball to 12. We played in several different megachurch leagues (that we were never a member of) with the kids over the years, but not this one.
So, after several emails from the director saying they would have to cancel the U12 season if they didn't get coaches, I volunteered. I know basketball decently, but not really enough to coach that age, but it was either that or he wouldn't get to play. So I volunteered to coach, and the league was set.
A few days before the first practice, the director emails all the coaches to fill out some basic insurance info or whatever, but also a "declaration of faith." Every coach had to initial each section and sign like a seven page document enumerating their Christian beliefs, evangelical flavor. There was nothing about proselytizing to the kids, but you had to sign off on all these doctrinal things you believed in as a Christian to be allowed to coach.
WTF? I'd never heard of such a thing. I'm Christian, but I'm a practicing Catholic, and it rubbed me the wrong way, so I just ignored it, until I got a stern email that I had to have it in. So I looked at it, and the vast majority of it were things that I could comfortably attest too without being in conflict with my Catholic faith no problem. But there were two bullet points that were not. So I was about to be blackballed out of coaching, my son's team not having a coach, etc.
So I eventually initialed all but those two, and sent back an email explaining that as a Catholic I was confident I met their requirements as a Christian, but I could not initial Section 4, article 2, point 6, and Section 13, subsection B, but everything else was initialed. And if that wasn't good enough I wouldn't be able to coach. Then the night before the first practice I got the email, "Ok fine, see you tomorrow."
The best thing was that I got assigned a group of total maniacs that were obnoxious, impossible to control, but really good little ballplayers, and we dominated the league to the championship. I couldn't control or coach them in any meaningful way, and after about the second practice all I would do it run loose ball drills, let them scrimmage, and play whatever that game is with two balls and you have to make a basket before the guy after you makes a basket. But we blew out everyone.