Love the idea of Bruce having insane knowledge of almost every single sport known to god because of his children.
He used to watch every gymnastics championship because 12 yo Dick Grayson loved to say "I could do that" while watching the competitors and then he would try it (and ace it). Alfred urges Bruce to get Dick to join his school's gymnastics team after dropping the TV an breaking a vase, Dick loves the idea of being on the spotlight again and Bruce becomes DEDICATED to learn everything possible thing about the rules so he could help Dick train for competitions. Bruce is the kind of dad to become really vocal about supporting his kid, that gets him banned, eventually, from a tournament after the judges gave Dick an unfair score and Bruce made very cleare his discontent, Dick can't even get mad, he's too busy laughing his ass off after finding Bruce brooding on the sidewalk.
In an attempt to spend more quality time with Jason out of the costumes he tries to teach him how to play baseball, they both suck, but Jay gets so into the sport that he forces Bruce to watch every game with him, so the man ends up learning the rules along with his kid and they go out to play every weekend. Even now, every once in a while, a ticket to go see the Gotham knights game with Jason would mysteriously appear on Bruce's desk.
Not long after Tim becomes Robin they have to solve the case of a guy who allegedly disappeared when going to skate, Robin asks to see the boy's bedroom and after watching the shoes he just states: "no, these are not the shoes of a skater, I would know, someone's lying to us." He turns to be right and Bruce congratulates him and that is it for a while. Until Jack Drake dies and it gets harder to see Tim go out on the day and it worries Bruce deeply. That somehow leads to Tim going to the garden looking for Alfred and instead finding Bruce falling on his butt after trying to get down of a skateboard in movement, Tim laughs, confused, and Bruce just awkwardly smiles: "wanted to try and learn so we could have something to do other than solving cases". Tim passes the next three hours and a half teaching Bruce basic skateboard skills. It becomes a tradition for Bruce to learn a trick or two from Tim when any of them is too stressed out to function correctly.
Bruce catches Cass watching ballet on TV once and immediately books a ticket to see the next Nutcracker show in Gotham, Selina finds out and starts planning more and more ballet dates with Bruce, asking him to extend her invitation to Cass. When his daughter starts showing interest in practicing it as well, Bruce searches everywhere for the best academy in Gotham and Cass starts receiving leotards and leg warmers every other week soon after that. On the day Cass announces she's now allowed to use pointe shoes Bruce dissappears into his study and comes back with the shoes he had been saving for her since she entered the academy and tells her he is proud. And if Bruce cries the first time Cass gets a solo, well, that's a secret for them to keep.
After watching Damian play football (soccer) for an uncover mission, Bruce urges his son to not leave the team, Damian insists he just played because of the mission and refuses to get into the sport, claiming there's no point in learning something that won't represent a real challenge for him, Bruce decides there and then that he's going to convince Damian one way or another. He starts loudly playing every single Gotham game on the TV and making it everyone's problem, on the fifth week on a row Damian gives up, finally sitting next to his father. It's Gotham vs Star City that night, the first of the season, and Gotham loses BADLY, Bruce thinks that that is it, Damian is going to lose interest, but no, something worse happens... Damian starts supporting Star City. So Bruce rants about it to Dick who laughs at him and tells Barbara, but then Barbara tells Dinah and Dinah tells Ollie and Oliie starts inviting Bruce and Damian to watch the games at his mansion, Damian doesn't really care about watching them with the Queen family, but Clark tells Bruce that it would be rude not to go and so Bruce has to sit there, suffering in silence because holy shit, he did not know Gotham had this kind of losing streak against Star City out of all teams. He watches as Damian celebrates a goal with Emiko and Lian as Ollie AND Roy turn to look at him mockingly and Bruce can just sigh as Dinah (the other Gothamite tough and trough) pats his back, used to it. Hey, at least Damian doesn't leave his high school team and Bruce gets to support him on his matches and send Talia pictures of Damian holding trophies every single tournament.
He watches Tim lose badly against Duke on a game of chess and he gets excited because, FINALLY, something he already knows how to play. He tells Duke to go against him next, ignoring Tim begging him to run while he still can. Duke wins in less than five minutes, leaving Bruce flabbergasted, and just says 'if you want to go toe to toe with Gotham high's chess representative you need to get better, old man'. Bruce brings out the board every two weeks or so, telling Duke that he IS ready now and to not go easy on him, he never wins, but his time does get better, he's sure he'll get there, eventually.