The context of this question isn't so much to figure out what skills a developer needs, obviously for each project there are different technical and marketing challenges that need to be addressed. I'm asking more from an intangible, team-building sense what you can use to figure out if your team will gel or not and also if there are any good techniques for figuring out synergy early on.
One of the most powerful personality traits I would look for is humility. There is nothing worse than trying to get on with someone who is convinced he/she already knows everything and already has all the answers. They are not open to discussion, exploring other ideas or even slightly letting go of what they already "know" to be right.
Another important trait is tolerance. People are different, fact. And when different people work together closely they are bound to get on each others nerves from time to time. One must be tolerant of this and persevere through the tough times rather than throw in the towel at the first argument. Obviously if arguments are huge and happening every day, that's a different story. But disagreement must be reasonably expected and it is incumbent upon each person to tolerate that and move on.
Those are the first two qualities that came to my mind immediately.
Tries you should look for in a Co-founder,
1 = Complementary strengths: Recognizing your strengths makes it easy to define your roles in the partnership, and that definition makes it easier to hold one another accountable as the business grows. When you run into difficulties in making a decision, it’s nice to have someone who can see things from a fresh perspective.
2 = A Thirst for Knowledge: A perfect co-founder is one who recognizes that he or she hasa lot more to learn. This recognition that the individual doesn't have it all figured out, coupled with a willingness to learn, will greatly contribute to growth in the right direction.
3 = Shared Passion: A co-founder who brings a financial investment is terrific --and might be the one thing you need to get a startup off the ground. But, even more important --and hard to find --is a co-founder who recognizes your drive, missionand passion, and shares it.
4 = Adaptability: Having a business partner who is able to think on his feet and adapt to changing situations is critical. In any new business, you’re likely to encounter a fair number of surprises, so find someone who won’t sweat the small stuff and can be flexible when the going gets rough and tough decisions need to be made.
5 = Serious Energy: You might think you’ve got enough energy for the team, but you always want to be backed up by someone that has at least as much, if not more, than you. Starting a business is hard work, and it’s not for the faint of heart.
I'd agree with Paddy, though every skill has to be in equal measure and there is no way to determine whether a Co-founder will necessarily be a good one or a bad one.
They have to have personal drive, this is essential, and I don't mean the kind that says, 'I'll do a couple of hours on the weekend'... personal drive means, and I like the analogy, Military, Army style 'Determination'. Think of yourself as haven crashed out in the desert with your Co-Founder / Partner: you have limited resources, water, food, raw materials. It's hot, and cold at night, you have 200 miles to walk but you don't know in which direction, you don't know if your walking in a straight line or if your walking toward more danger.
The road is long, very very hard and you're alone.
Sometimes you see a mirage, the fountain of everything you dream of,,, help, love, support, and cash, but 80% of the time, it's just a mirage.
Now, think, is this Co-Founder the kind of person who can go the distance? be creative with what they have and make new resources? push forward when you're tired and respect when you push them.
Piss off your Co-founder, really piss them off and see if they buckle and throw everything away, because you're guaranteed to do it later in the future, why not try it now early on.
They also need to be able to make decisions on their own, but more importantly confer that a decision needs to be made.
The key is though... they have have have to be worth it, they have to contribute and do their part.
With my analogy, who will make a fire a night? who will resource food? create a shelter? who will lead? will they follow you??
You can do team building exercises by creating a task like: organising a BBQ... send out invitations, organising fund raising, purchasing, operations and preparations, marketing, feedback and quality control. If you make a good team then you'll be good, at least for now.
It's not easy to say it shortly. It depends on the profile of the cofounder you look for. If more entrepreneurial figure then the following are essential:
Re the team-building sense there are capable leaders recognized by their team members to finally come out with a balanced team in functional backgrounds competencies and skills...
There are six primary business skills you (and every company) need to master. 1) marketing, 2) sales, 3) organization, 4) efficiency, 5) people, 6) leadership. Very few business owners ever master more than 2 of these skills, so you need to fill these skill gaps with other people. Beyond that it is style, interest, and commitment. Techniques for figuring out whether you have a style clash? That falls under the People category, learning how to effectively interview.
I always want to dig in to understand what someone believes in. What is their own personal why. From that, you can usually figure out if there is synergies between the way you both think and operate and can build from there.
Every person has its own personality so you must look a person a skill and their interest the same as
A willing heart is Number One factor to consider in forming a synergy of confounders.,
Most of the Application developers has More to Offer with (CAN DO) Spirit.
Seek for Loyalty too in seeking a Cofounder.
I've just found an investment partner myself. To answer the question, honesty and trustworthiness, enough sustained enthusiasm (someone with get up and go), willingness to be reasonable, and sound judgement would all seem musts, especially if that partner is going to be a joint director with you. This is someone you are going to have to work with and is quite rightly a big commitment.