With respectable bulk and good abilities in Hydration and Water Absorb, Lapras can be a potent threat in the VGC 2012 metagame. A low base 60 Speed makes Lapras a good candidate for Trick Room teams, and it is able to work well in different weather conditions. While it does have these perks, Lapras also has its drawbacks; Lapras's paltry base 85 offensive stats mean that even a physical Latios will hit harder. Still, with the right team support, Lapras is a threat that must be prepared for.
This set takes advantage of Lapras's main attributes: bulk and access to Hydration. The idea is to come in while rain is up, take a Water-type attack to activate Absorb Bulb, and proceed to repeatedly attack with STAB rain-boosted Surf. The choice of Thunder or Ice Beam comes down to what you need Lapras to take out. Thunder has perfect accuracy in the rain, but leaves Lapras susceptible to Dragon-types. On the other hand, Ice Beam is an option to take out the Dragon-types that will stop Lapras, but it will allow rain teams to walk all over it.
The final two moveslots are the bread and butter of this set. Rest provides full recovery, and, in the rain, Lapras's sleep is cured at the end of the turn, courtesy of Hydration. Protect is standard in the VGC metagame to ease prediction and recover HP, if opting for Leftovers. Team Options & Additional Comments >>>
While Lapras is typically seen playing a defensive role, this set aims to capitalize on an incorrect prediction and KO specific threats that counter Lapras. For example, Yache Berry Garchomp will survive a +1 Ice Beam from the defensive set; however, the same Garchomp is OHKOed by an Ice Gem-boosted Blizzard. Other examples include Dragonite (with Multiscale), Latios, and even Zapdos.
The other three moves come down to supporting the primary STAB option, Blizzard. Surf provides a secondary STAB move, taking out Fire-types that resist Blizzard as well as 2HKOing Tyranitar outside of sand. Ice Shard will help deal with Focus Sash users such as Chandelure; however, if they aren't problems, then Thunderbolt can be used to take out Water-types, most of whom would otherwise wall this set. Protect is, once again, standard in VGC.Team Options & Additional Comments >>>
Outside of what is listed, Lapras has a very shallow movepool. Perish Song can be used, but you have to make sure that you have at least one Pokemon left in reserve. Sheer Cold is somewhat viable due to Lapras's bulk, but is gimmicky at best and viable only on the Hydration set. Sing is another option as sleep is always beneficial, but its accuracy is shaky. Psychic can be used to stop Fighting-types, but the only notable OHKO that it gets is on Toxicroak, who can KO Lapras after a Fake Out anyways. One final change you could make is to use Scald or Hydro Pump as Lapras's STAB move. Scald would be beneficial for the Hydration set by providing burn support for the team, while Hydro Pump could help the offensive set by providing a more powerful STAB attack; the choice comes down to a matter of power versus accuracy.
There are two other item options Lapras can use. First, Sitrus Berry can be used to improve Lapras's longevity. Chople Berry is another option, helping against the Fighting-types that threaten Lapras. However, Pokemon such as Infernape and Terrakion can still OHKO it with Close Combat whether or not Lapras carries a Chople Berry.
Checks and Counters
Fighting-types, such as Hitmontop, Terrakion, and Infernape, are the best counters to Lapras, as they can all OHKO it with Close Combat. Water-types in general wall Lapras well, though they must be careful of Thunder or Thunderbolt; Rotom-W stands out among the bulky Water-types, as it is able to wall Lapras even if it has Thunder or Thunderbolt. Lapras depends very much on the weather for it to be successful; as such, Tyranitar stands out as a good counter—it gains a Special Defense boost in the sand and can hit Lapras hard with its STAB Rock Slide. Finally, in rain, Ludicolo and Abomasnow are major pains to Lapras, taking only neutral damage from any of its moves and KOing Lapras with a Grass-type attack.