In MOBAs (LoL, HoN, Dota, etc.) occasionally you'll get paired vs. a strong laning combo with heavy harassment potential in a dual lane (such that coming near the creeps to lasthit/fight/counterharass will only get your char's head bit off). In cases where you both can and cannot trust your laning partner (as in, you know he's good vs you know he's not good), what are your options to deal with this?
If you're against a strong laning combo and you cannot rely on your own laning partner, your best bet is to keep your minions between you and the other champions and to use your front-most tower as a "third man".
If you stand behind your minions and out of range of your opponents, you can take potshots at the enemy champions when they are open, get the killing blow on enemy minions when those potshots are not safe to get, and reap the experience and levels from the minion kills. You can coast through your first several levels this way, gain new abilities, and buy gear to counter the champions you're up against (armor against melee, magic resist vs. mages, etc). Your laning partner will also benefit from this, provided they aren't trying to tank the enemy champions past your minion wall.
Hanging out near your front-most tower will result in minions dying faster (and getting you more experience), opening up more "last hits" (since if a tower hits a minion with full health, it gets knocked down into its "one more hit" range, and makes it that much harder to get harassed or ganked.
This strategy will hold you over until after the initial laning phase, when the enemy team starts coordinating ganks and tower takedowns. At that point, you should be powerful enough to be more viable and will be able to use that advantage coupled with team coordination to push back any encroachment, snag a few kills, and take advantage of their temporarily-reduced champion count to push a tower in a weak lane.
If you can rely on your laning partner but you're still not confident that you have the right composition to go against your competition, the same strategy works as well. In this case, you'd have yourself and your lane partner buy items that can help mitigate the effectiveness of the competition, including defending against their damage type, buffing damage types they are weak against, and making sure your movement speed is faster.
One thing to keep in mind is you should keep checking on the items your competition is purchasing. In many cases, the competition won't be paying attention and will be using general item specs, which means you can more easily counter what they are buying. Monitoring the items the competition is using is important in any game, but is even more important if they start with a composition advantage.
In addition, if you managed to get a competent jungler on your team, exploit the advantage of additional experience, gold, and the ability to put pressure on random lanes to mitigate enemy effectiveness.
Above all else, don't die, and stress to your laning partner that they should do their best to stay back and away from possible gank distance. Deaths mean extra gold and experience for the other team, which will only worsen your situation.