Subs should get ult charge when they join match.

Obviously when a match has literally just started they don't need it. But when you join a match that's already been going on for 1 or 2 rounds you need some sort of ult charge because in a game all about ult economy it's difficult to keep up when you're constantly getting ult dumped on and you don't have time to farm ult.

Having the average of your teams current ult charge wouldn't be bad so if everyone has around 50% you can also start the game with 50% ult charge to make it at least a fair fight when you join.