Couple of tips.
When it's 2 on 2, or 3 on 2, or whatever, and the other team has stupidly sent all remaining players to lay seige to your fortress, go ahead and send your co-defender to take the other zone. Seems like a no-brainer when you think about it. If that leaves your zone with two attackers and one goalie, it's probably ok. The goalie then needs to open up his zone and kill one attacker. The open space in the zone is too tempting for the other, he'll try to take it instead of falling back to defend his own. You just need to hold it. But opening the zone and letting him in is crucial for it to work. If he doesn't think he can take it, he'll fall back to protect his own fortress. If they send one or two attackers back anyway, then you've just turned it into 2 1 on 1 fights instead of 1 2 on 2 fight. It's easier to fight the two separate 1 on 1 fights than it is to fight the 2 on 2 fight, it's the zone that tips it in the attackers' favor.
When running a double goalie and you're being attacked in force (say by a factor of at least 2:1), the inner goalie should pull himself in deep in his zone so the outer goalie can chase his own tail, like a regular tail-chasing goalie. Anybody who manages to break through the space between his tail and his cycle will encounter a zone full of walls--they can't take it. Knowing this, the outer goalie should let one person in until he's dead, then let another in, and in the meantime kill whoever he can. By letting one person in, he relieves the pressure on himself, and sends that guy into almost certain death. This also deals with the fact that the other team will have enough torpedos to blast through both walls. So it prevents the torpedo attack that might otherwise work and forces the other team to fight you one at a time, while you can put two together to fight them.
When you're by yourself and you're being attacked by 2 people, open up half your zone. Do it piecemeal, but open it up nonetheless. One of the attackers will fill it, no doubt. Kill the other one first, then deal with the one in your zone. While it seems like a reverse of priorities, it works because the guy in the zone doesn't want to give up the space he's taken for himself, and the guy outside the zone will do whatever he can to get in and turn it over. He's easier to kill, and you can just sumo the guy inside the zone afterwards.
On a large team (6-7 people), you're stuck with a wedge, right? You need to fill in the wedge as soon as possible. If one of your teammates circles you for a little while after the break, he can defend your wedge, which is the weakest part of your defense. You can fill it in then and finish setting up properly.
Also, on a large team, by the time you come around to where your wedge is, one of the other team's attackers could easily have found a way down the middle. So on a large team, you're particularly exposed to center attacks rather than side attacks. So close the center like normal, then turn out, again, like normal. When you are on the part of the circuit that has you facing the wall behind the zone, glance and see how the offense is doing. If a center attack is going to be coming, you should be able to see the signs of it. If you see it, go ahead and cross over and seal again. It screws up your zone a little bit, making it take longer to setup, but it does counter the center attack that's coming, and as long as they don't send some more people down at the same time, you can repair your defense before another attacker arrives.
Again, on a large team, if someone circles you while you're setting up, you can grind their wall for speed. This lets you setup faster, albeit in a more regular shape. You can always put bumps in your walls after you've done your first setup.
So on a large team, you really should have someone circle you while you're setting up. He can cover your weak areas, giving you a chance to get setup that you wouldn't otherwise have, and you can grind his wall for speed to setup faster.
The counter to the torpedo attack is surprisingly simple. Watch for it. At a certain distance from your wall, they are committed and can't pull off without risking killing themselves for nothing. If the torpedo pulls off, the other guy might still hit. If the other guy pulls off, the torpedo might still hit. At that magical moment when they are committed, turn back and box the area they're going to hit. 4 points!
I also found that antagonizing the attackers strengthened my defense. So whenever I laid a trap and they just walked in, I'd talk trash. That made them more anxious to take the zone, and more likely to walk into future traps I might lay for them.
Judicious use of brakes as the goalie can really screw over an attacker. I racked up quite a few points by watching where they expected the gap to appear, and hitting my brake. 2 points!
Use the scoreboard to your advantage. If you have 90 points and there are 7 people on each team, don't even go for the fortress. Move that way, of course, to prevent too many of the other team from being in your backfield together. Otherwise, try to kill them instead. On large teams, you can start worrying about this when you have 76 points. The math works out.
7 * 2 = 14. 76+14=90. 10 points for the round gives you 100 points, and you win. Try to maximize your yield from each round by killing a few players. If your entire offensive team dies, but manages to get 4-5 of the other team's players, that's fine. Sure the other team just got 6 points of their own, but you now have a numerical advantage plus a profit on points (compared to what you gave up to get it). So keep an eye on that scoreboard! With large teams, you can win most of the rounds and still lose the game, if you're giving up too many points each round. Keeping that in mind, if the other team gets you in a box or something, try to do whatever you can to turn it into either a suicide or a teamkill. This last part might be considered a dirty tactic.
Ah, one last one. Practice at sumo.
Definitely. Get over the idea that the zone is yours and yours alone. If you can sumo, and other people on your team can sumo, then they can enter your zone to help you defend. Remember, if 2 attackers enter your zone, they can take it from you. But if another defender enters your zone, you can hold it, and even push the other two out. Yeah, chances are good one of you will be dead, but chances are even better both of the attackers will be dead too. So be ready to defend your zone with one of your teammates inside it to help you. And don't be shy about going in--if you know the goalie can handle it. Settle it later if you have to. If you screw up and the other team wins, well they would've won anyway. But if you do it right, you repel the other team.
