Q.Can I plant a few Contender /Garden Beans in a long patio pot with a trellis?
Trying to plant Mini garden on 2 floor porch of an apartment with the kids, we have a variety of herbs and lettuce/tomatoes growing.
Some Peas with a twine trellis. What pairs well with “String Beans”?

Certified GKH Gardening Expert
As long as you have, at least, an 8 gallon container, then you can companion plant with beans rather easily. Just be mindful of what you plant, and stick to those that are suitable to plant with beans.
This article will help: https://www.gardeningknowhow.com/edible/vegetables/beans/bean-plant-companions.htm
And this article will give you information on growing beans in container: https://www.gardeningknowhow.com/edible/vegetables/beans/growing-beans-in-containers.htm