I’d be in favour of a single, short, unblockable pause. Because I’ve had experience with people who unpause me immediately, and it feels bad. At least there should be enough time to explain the reason for the pause.
Most games my opponents aren’t trolls, and if I get trolled for a short time in some of my games, I think it’s worth it.
Capping the amount of pauses available is tricky. If you both agree to pause the game for 30 minutes, or to pause the game every 5 minutes, it should be possible imo. But OTOH if one player keeps pausing and the other player doesn’t want to pause the player who keeps pausing is just being a douche.
Maybe a good solution would be that both teams start with 2 pauses available, and when one team uses a pause the other team gets a pause.
That way trolls can only pause twice, but if you’re cooperating you can pause as often as you want.
In free-for-alls you could give all players an extra pause when all players have used at least on pause.