I want to talk about some of the problems that you will encounter wtih your vision of the game.
The whitelist is interesting. Some of the banned items make good sense but some bans I do not understand (like Force-a-Nature).
This is the biggest issue: The official Pass Time maps that are in the game are HUGE. They're WAY too big for 6v6. In fact even in pubs with 12v12 they seem too big often times. Also for the most part they don't seem very thoughtfully designed at all. For example, with pass_brickyard, while I love that map and it was what originally inspired me to look into Pass Time as having potential to be really fun and awesome, it was designed as if Sniper is not a class in the game. Sniper is so ridiculously dominant there that it's awful. The only good thing you could say about the large maps is that they compliment the long respawn times. This leads into the other issue which I think is the wrong direction for Pass Time. As it is now the focus would be like regular TF2 (or most any other [shooting] game)-- To kill the enemy players. Then they're all dead, or outnumbered and forced to run away, and then you achieve the objective (score goal). If you look at tf2 bball or Rocket League or my 4v4 Pass Time dying is rarely a huge deal as you respawn again in seconds so killing the enemy team just so there's no one to stop you is not the strategy and death is rarely consequential. If you do kill the enemy players you have a window of mere seconds to try and go on that opening. Actually playing the ball and defending your goal and setting up teamwork plays is what I think should be happening in a sport/ball type game.
I'm not all-knowing but I bet I can theorize some of the tactics that will be employed in your game. First, both teams would travel in a pack. The team that has the ball would try to avoid fighting the defending team because they are down a gun (whoever is carrying the ball). They would try to get around the enemy pack. Then again if the scout is carrying the ball then all allies close by would have scout speed so maybe it's not such a disadvantage. So maybe they would try to fight the enemy team. Perhaps throw the ball in a corner real quick, win the fight, then pick it back up. But what about, if the moment the defending pack approaches the attackers launch their soldier forward and break away into enemy territory to score. He can throw the ball forward (and up high) then catch up to it with a rocket jump and repeat that over and over. Or even better, why not launch a fully buffed demoman who walks at scout speed with a double sticky jump and have him clear the entire map and then he can score. He could shoot into the hoop or just fly into the football endzone. Sounds like you'd need to leave a defender back by your goals but I'm not sure even a sentry gun can reliably stop some of these attacks (like a mega fast demo) if for no other reason then there being 2-3 available goals to score on. And then if there is some decent way to defend does that sound like a fun job that someone wants to do? Sitting all the way on your end of a giant map and waiting around? If there's no defender then most good breakaways would be free goals. Or what about if a team just uselessly passes the ball back and forth a dozen times to open up the bonus watertower goal and then launches their demo up there for a quick score? I guess you could sometimes stop him with a sniper or a DH shot? Even a demoknight could be used in messed up ways on some of those maps. It wouldn't look exactly like this video, but similar ( https://www.youtube.com/watch?v=V268-El7pXQ
Now maybe I'm just too dense or cynical to see how awesome these games could end up being but I think that between the maps, the classes, and all the unlocks, if you are indeed playing your hardest to win then this will evolve into an utterly degenerate game mode. People will figure out the lamest and most unfun ways to play it and to win and in the end it will not be a good time and people will bury the idea of anything good coming from Pass Time.
To contrast this my map is small with only one goal. The rules limit the classes and items allowed. Most items are NOT allowed because the focus is not on finding the most unfun way to ruin the experience and break the gamemode. The focus is on rocket jumping, surfing damage, airshots, and setting up tight plays with teamwork. My 4v4 Pass Time is like the 6s of Pass Time the way 6s compares to pubs. It's unapologetically geared towards competitive players, bballers, jump mappers and the like with a high demand for mechanical skill and is intense and action packed and very satisfying. You can check the few videos on my channel (though they're bad quality and a bit outdated) as well as some stuff that Laxson recorded.