The Best Tapu
Psychic Terrain
Choice Scarf/Choice Specs
Timid 252 SpAtk/252 Speed/4 SpDef
Psychic
Moonblast
Hidden Power Fire
Focus Blast/Thunderbolt/Psyshock
One of the guardian deities and arguably the best one of the bunch, and for good reason. Ability of choice is psychic terrain, which is arguably the best terrain move not only for Lele but for general team support as well. With psychic terrain, Lele's psychic type moves are boosted in power and all priority moves fail which means Lele can't be revenge killed by Mega Scizor's bullet punch, among other things. Lele's stats allow it to be an amazing choice user. Psychic is STAB of choice because under psychic terrain and with Lele's incredible base 130 special attack, it hits anything that doesn't resist it ridiculously hard. Moonblast is coverage for dark types and secondary STAB. Hidden Power Fire hits steels which otherwise wall Lele to death. The last move depends on what coverage you want. Focus blast hits some steels, such as Magnezone, harder than hidden power fire. Thunderbolt hits Celesteela harder than the other two mentioned coverage moves. If you decide to use specs, Psyshock is an interesting move for the last slot. While the coverage may seem redundant, it allows you to break through specially bulky mons such as Chansey very easily, which allows other teammates to sweep.
Tauntpu Lele
Psychic Terrain
Fightinium Z
Timid 252 SpAtk/252 Speed/252 SpDef
Psyshock
Moonblast
Taunt
Focus Blast
With taunt, Tapu Lele can easily shut down stall and set up pokemon. Psyshock is the STAB of choice to hit pokemon with lower physical defense hard, while moonblast hits pokemon with lower special defense hard. Focus blast and a fightinium z are used to nuke any steel type that decides to try to take you on.
Checks and Counters:
It is very hard to counter Tapu Lele without knowing what set you're running, and even then you still have to be wary of what move Lele decides to use if choiced and what item it's holding if not. Steel types generally make good checks if they don't switch into HP Fire/Focus blast or get hit by a fightinium z boosted focus blast. Things like Assault Vest Magearna, Celesteela, and Magnezone can all deal significant damage to Tapu Lele, but have to be wary of the set and don't like switching into Focus Blast/Hidden Power Fire, although AV Mag takes those hits better than its other companions. All three mentioned pokemon also have to be wary of switching in multiple times since Magearna and Magnezone lack recovery altogether, Celesteela has very passive recovery in leech seed. Fast dark types can switch in to a choice locked Lele and can deal heavy damage back, but generally can't take a moonblast from any set. Specially defensive mons such as Chansey check any Lele not running psyshock rather well, but it's impossible to tell whether or not Lele is running psyshock, even if it has already used psychic since people do run both for this reason.
A special mention here is Assault Vest Alolan Muk. Assault Vest Alolan Muk can take any hit Tapu Lele has to offer and either pursuit trap it or KO with Poison Jab. However, it does not like switching in to repeated moonblasts and is threatened by a plethora of other Pokemon that could potentially be on the same team as Lele.
