Warwick is good in jungle and has great attack (with more experience and speed) it can up faster for assisting in killing sooner. He is physical damage.

ChoGath is a good tank, with a stunning and silence hard to hit, but in partner with Warwick, can kill any opponent. He is mage damage.

Teemo is good in mid, with ranged attack and damage. Swift and stealthy it can help quickly at top or bot, and put mushrooms to take land control. He is ranged damage.

Zilean is an immortal one for top turret, even against two opponents, but staying close to your tower. Opponents should bother to attack Zilean, because he up much faster (by experience bonus and fight alone).

Janna must ensure bot turret, up to level 6 will partner with ChoGath, and then turns alone on land.

Beginning of the game (until level 6): This team is fast and should not worry about killing opponents, let them attack you. Stay close to your turrets, kill a few minions, the ability to spend champion.

Another option is ChoGath go solo at top, Janna and Zilean go together on bot. The advantage is that Cho will up faster to help Strike Team.

Middle of the game (level 6 to 12): Zilean and Janna are virtually fixed at ends, but in emergencies can defend the middle.
Strike team: the attacking trio (Warwick, Cho and Teemo), must know how to play separate, but unite to attack.
Explain:
Teemo is still official mid, but you can trade with others to help Zilean or Janna.
Warwick is still Jungler, make sure you get buffs, but wait to attack with team. The towers will fall easier if Warwick is attack speed and damage, many people prefer same wizard to jungle, but in this team's the Attack Speed and Movement Speed play much more.
ChoGath, you need to be enormous and immortal, do not risk yourself, make Warmorg and eat minions, return to base if needed. When towers are destroyed, the basic strategy of the opponent will come together, and you will be responsible for receiving up the damage.

End of game (level 12 to 18): the towers are no longer major problems.
If opposing team has some beginners, the best strategy to stay whole team in the opposing jungle, waiting a couple of noobs, to kill them and then go up the towers and inhibitors.
If opposing team is good, the best strategy is to wait (Zilean and Janna in edges, Strike Team together in mid). Until we have killed some, and go kill Baron, with Cho and Warwick this is possible! Take the buff, return base, and then all the way up opponent. The safest is to destroy an inhibitor at time, with three out, we going to destroy Nexus, but of course it depends a lot.

When all go mid, the strategy is Cho and Warwick in front.
Zilean supports Warwick with speed and immortality.
Janna supports Cho with shell and area blows that play opponent into air (can be combined with attack of Cho).
Cho and Warwick should not be too far from Zilean and Janna, therefore must protect them after receiving their buffs, and they will still be of great help in magical damage.
Teemo is independent. He must hunt when the opponents run, and should return base or turret when that are attacked while the rest of team attacks.


Remembering always: an XP and Speed team should prioritize survive.
XP does mean you get not depends on killing many opponents, you can wait and see when they come. You will be at the highest level.
Speed means you can come back to base, since it will hurry back to your post. Its great to think about getting Quintessence of Gold and items as Avarice and Kage Luck.

Cautions:
Opposing teams with many killers, stand in defense is not as easy as it looks. Skills (Fortify, Teleport, Cleanse) are decisive in bad times of team.
Opposing teams with area damage is a problem for Strike team. One good option is go to jungle, because in restricted area these attacks dont have full effect.
Opposing teams with many tanks, attack and poison may be unnecessary and wastes energy. Let ChoGath in front, receiving attack and eat minions to regenerate. When they mana running low, become easier targets.

Substitutes:
You can replace the Strike Team if you want:
Balanced team
Teemo, ChoGath, Warwick
Defensive team
Heimerdinger, another tank, Amumu or Nunu
Aggressive Time
Ashe or Miss Fortune, Garen, Thyndamere