IMO You're better off applying on your own and stating your intention to find a cofounder.
YC does occasionally accept sole-founders who plan to find someone else, as far as I know (I may be wrong) they've never accepted a team which was put together by strangers for the purpose of YC.
YC places a huge emphasis on team (over everything else in the application) and team dynamics play an important part in that. They need to know the team won't fall apart when under pressure as that's one of the main reasons startups fail. If you pair up with someone you've never worked with, then neither you or YC have any indication how the team dynamics will work.
YC does occasionally accept sole-founders who plan to find someone else, as far as I know (I may be wrong) they've never accepted a team which was put together by strangers for the purpose of YC.
YC places a huge emphasis on team (over everything else in the application) and team dynamics play an important part in that. They need to know the team won't fall apart when under pressure as that's one of the main reasons startups fail. If you pair up with someone you've never worked with, then neither you or YC have any indication how the team dynamics will work.