I would assume that trapping like that is much more difficult to pull off efficiently and consistently ever since Mew left UU. It can work, and there are a number of Pokemon that have a combination of moves and stats that can do the job ok, but that doesn't mean that they are viable in any way. Fast Encore/Leech Seed/Infestation Jumpluff can do a lot of work, so if you REALLY want to try something like it, give it a shot. Bear in mind that its situational at best, and isn't nearly as good as Infestation Mew of the past.