Short Answer: No
Long Answer: It's genuinely something that may seem fun to use in low ladder, but it's just not viable. When you look at the viability rankings as well as usage stats, there's the omnipresent Yveltal. Since Dark-types are immune to Prankster priority, Yveltal can easily shrug off anything you try to throw at it. There are some other counters as well, such as Ferrothorn (immune to Leech Seed because of grass-typing).
2 | Yveltal | 58.52158%
Yveltal has the second highest usage, with over half of the teams running it. As already told that Leech Seed priority Prankster is not doing anything to Yveltal, it's just falling off viability.
Tl;dr don't use Cottone strategy in AG, because of how common is Yveltal and its immunity as a dark-type makes Cottonee a bad choice to use.
Hope this answers the question.