Cones can offer a lot of slip, but in my opinion it may be best to avoid them if you don't regularly clarify. Some people have had breakage and dryness issues that resulted from overuse of cones without regular clarifying.
I almost exclusively cowash so I would recommend either adding oils to your co wash conditioner if your hair likes oils, or trying the kiya fizzle, which my hair loves. I add a teaspoon of conditioner to my nature's gate jojoba condish, apply it to my hair in sections, clip up in a shower cap, let it sit while I shower and then detangle in sections under the shower head. This has given me the most slip ever. I then add additional moisturizing conditioner and leave it in. This is my big detangle cowash day. I also DC overnight on dry hair and rinse and go as well as use my DC as a leave in. I only detangle once a week, and usually I only cowash once but sometimes twice.
I hope that made sense...