While Tapu Lele should always be used over Gardevoir for any meta team, I'm not sure that it's the best choice for a team that uses Belly Drum Azumarill as a win condition since Psychic Terrain nullifies Azumarill's Aqua Jet. Even though there's a Tapu Bulu on the team as well to change the terrain, I would still imagine that you wouldn't want to risk being an awkward position where you want to sweep with Azumarill, but Psychic Terrain is up and you need Aqua Jet and you're forced to go into Tapu Bulu to change the terrain before finding another opportunity to set up. Speaking of Tapu Bulu, if Garchomp's being used as the main wallbreaker, having Grassy Terrain up might hinder its ability to perform its role due to the terrain weakening its Earthquake. I'm still trying to learn the meta, though, after being out of the loop for a while, so correct me if what I'm saying isn't as much of a concern as I think it is.