I carry a spare tube/self-adhesive patches/Dynaplug kit,and a mini-pump along with a couple of Co2 cartridges. Co2 is near freezing when it comes out of the cartridge (freezes the sealant) so a mini-pump can sometimes help if the hole is close to the valve.
Also, don't rely too heavily on the plug kits - they do work but the last time I used one, it failed after a few miles. A spare tube comes in handy even with tubeless tires on occasion