If you're playing the marksman, I suggest
.
Her longer range is good for keeping Alistar at a distance, and Rocket Jump helps you get away easy. You also have her ultimate, which keeps Lucian farther away than his short range would like. Be sure to heavy focus Lucian though; if they go in, attach a an Explosive Charge to Lucian, hit him a few times, then Rocket Jump on top of him. Alistar is weak once he uses his combo, so he won't be able to defend Lucian.
If you're playing the support, I suggest
Or
.
Janna can shield Tristana when she goes in, and her slow keeps Lucian in a place more preferred. Her ultimate is a good way to recover and help you keep fighting, and Howling Gale, when timed right, can stop Alistar's Headbut. Remember though, when Janna uses Monsoon, don't run. Tristana thrives better when she keeps going, and the heal should be sufficient enough to allow you that time.
Leona is the more aggressive counterpart, but works well with Tristana's all in pattern. Once Alistar goes in, Leona can grab Lucian, then you two can focus him together. Since Alistar won't have any crowd control left to use, Lucian will likely be hit hard by this, and he'll be forced to run. Leona also has a much stronger ultimate for dueling, since it actually has an effect other than a self buff.
Hope this helps.