I wrote a blog post back in 2011 titled: 24 signs he's not right for you, and it is the single most visited and searched post on my blog. That says something... to me, it says people generally don't have guidance, good counsel, and or a model of what is good for a productive life, and what is not.
So I'm taking a twist on that post and doing it on what are the signs that a co-founder is not right for you. To summarize it, I would say the most important ingredients are around 1) shared vision, 2) shared values, and 3) practical complementary skills to execute. So here's my original curated list of signs that the guy or gal you are with or desperately pining after is not worth your time. Most of them point to NOT being a team player, meaning they put their own self before all else. Startups are a team sport. These are things I've noticed or heard
1. Lacking sense of urgency/accountability/ownership. Regularly having to "cat-herd", chase down or PM your "partner" is not reasonable. Don't be his or her "mom" or "dad". There's no time for baby-sitting - everyone should be pulling their own weight and then some. Having to follow up left and right to make sure items that said that were going to get done, get done. That items that weren't supposed to get done are not being magically put in front of more high priority items. It's exhausting. Often you'll find "experts" with tons of "experience" that come in that only know how to highlight areas that need work or give ideas, but are terrible at actually getting anything done. Be skeptical of all the "experts", look for recent actual experience with actual results, and then go and verify everything they said.
2. Having to hang out with them is a chore. You'd rather do anything else, and you do it only because you "should". If you don't like them as a person, you don't like their significant others, ... I'd see those as warning flags. Sometimes you grin and try and look past it. You can't fake it for long. (Well, there are plenty of examples where the only thing you do like about your cofounder is your friendship and hanging out. The work part sucks.)
3. Getting them to show up is a chore. Just like you don't want to hang out with your co-founder, your co-founder makes every excuse possible and doesn't show up to team meetings and events. This probably is an echo of #1... and #2. Showing up is 50% of the battle. Show up. On time (or early). Be present. It's hard enough as it is - why deal with someone that isn't pulling their weight and on top of it, is pulling the chance of success for the team, down? You're either in, or you're not. Simple.
4. Your "partner" challenges you, a lot - and not for the good of the team. Not just a lot, but on everything - even items they know nothing about. You burn so much time trying to get alignment, you often get nothing done. In fact, this cancerous "co-founder" will cause so much friction within the team that the company will likely just implode sooner or later. There's the opposite possibility too - where the "partner" doesn't challenge you and acts as if they have no accountability or reason to care for the success of the team/company.
5. Seeks the glory, money, or credit. Not a team player. Not, no matter how you want to look at it. I've had partners from many years ago (that are no longer partners) put their personal fame or put more value on money above all else. It doesn't work. Whether you have 2 or 5 people on the team, it's a SMALL team. Everyone is IN and everyone is working on the shared goal. It's a shared effort which means shared kudos. Each person does what they can for the team. The co-founders should do a whole lot more, together. ... or maybe everything about how the "cofounder" speaks, acts, writes... is begins with "I". For some reason, that's always a hint that they put "I" ahead of the "we".
6. Calls you "boss" or "bossy" - or the opposite, sees you as merely the "code monkey" or the business admin/office admin. A co-founder is a partnership. Yes, one will often have more voting rights than the other. It's still a partnership where you should be working together for the same team for a shared goal. Both business and technical need to be in partnership.
7. He/She daily talks about all of the other startups and companies out there - and how your startup together is not good enough. We call that nonproductive whining. Do something about it, focus on making your own startup/team better one step at a time. Too much brain power and time spent on looking at others means less time spent on execution.
8. He/She tries to set up meetings with investors and partners behind your back, often does not include you, even when as a team, everyone has agreed to focus on someone or something else. This is usually from a lack of vision and values alignment - you aren't playing for the same team. I have seen this from other startups as well - where one founder really wants to drive the investor conversations (but is not the CEO). There's multiple messages being sent out "there". The discombobulation has led to the company's implosion every single time I've seen this scenario. You can't be divided in a startup - you have to be all hands on deck on the team's shared success.
9. He/She still has their old job title, their old company, their old everything as their personal branding is more important that their relationship as a co-founder in the startup. It's just disrespectful - and shows they are not a team player. You and your "co-founder" are playing for different teams. I've seen people try and join our startup who never change their resume/job information while working with us or even after. I've had business partners that completely erase any past failures we've had together from their records (which personally, I think is weird). Actually, I've seen employees/colleagues do that in the past too - completely erase a job from their history after being part of the team for 1 or more years. Make mental note - people that curate for appearances are not good for the team (let alone, a startup). You're either IN, or you're not. And there's nothing in between.
10. His/Her family and friends are a weight on your cofounder. Literally, nothing - their family may know absolutely nothing about this startup. Unless you're in super secret squirrel stealth mode, that's a sign that you should walk away and separate, fast. Startups are hard enough - we don't have time for betrayals and hiding unnecessarily from people in our lives. Community, family and friend support is hugely helpful if anything. I couldn't imagine doing a startup again without everyone's support. The other side of this, is the cofounder may have a spouse/family that still just doesn't get what this cofounder/startup business means. ... or maybe the cofounder just hasn't figured out how to manage their personal life and it's affecting their work in a bad way. Whatever it is, have them figure it out fast - or move on.
Are there any others you'd like to add?