Hippopotas is the only Pokemon in Little Cup who can set up a permanent sandstorm. It usually finds its place on defensively oriented teams, aiding its team with sandstorm support which adds more residual damage to the opponent.
Unfortunately, Hippopotas is not as effective as its big brother Hippowdon is in OU. Hippowdon can easily switch into various physical threats and constantly phaze them and successfully heal its HP via Slack Off. However, in a metagame filled with offense, Hippopotas struggles to wall effectively. Furthermore, low Speed and Special Defense stats really hinder its ability to stay in for long periods of time. Even with these shortcomings, Hippopotas is still a very dependable Pokemon. It can consistently set up both sandstorm and Stealth Rock, a claim no other Little Cup Pokemon can make.
Hippopotas plays a very important role in the Little Cup metagame; it is the only Pokemon who can set up a permanent sandstorm. This makes it a very effective Pokemon in the lead position, setting up Stealth Rock without much trouble and having a chance to disable the opponent's Focus Sash due to the sandstorm. With its great physical bulk it also makes a great switch-in to many physically-based threats who can be troublesome, such as Meowth, Aron, and Larvitar.
Stealth Rock is a helpful move for both Hippopotas and its team, as many Pokemon who are immune or resistant to Hippopotas's Earthquake, such as Paras and Mantyke, take upwards of 25% damage from it. Earthquake offers Hippopotas a reliable STAB attack to use, dealing decent damage. Crunch and Rock Slide are two options that provide excellent coverage in conjunction with Earthquake. Crunch helps Hippopotas combat Gastly and Duskull, two common switch-ins, while Rock Slide deals heavy damage to Flying-types, such as Mantyke and Taillow. Deciding the final move is quite difficult. Slack Off allows Hippopotas to recover a lot of its health to keep on switching in and tanking; however, in a metagame filled with Pokemon OHKOing and 2HKOing other Pokemon, it may be hard to pull off. Another issue is that lot of Pokemon can set up against Hippopotas with impunity. Gligar can easily pull off Swords Dance and sweep with insanely strong Earthquakes, Dratini can set up Dragon Dance reasonably well and destroy Hippopotas with Waterfall, while Krabby can set up both Agility and Swords Dance and sweep with boosted Crabhammers. This is where Roar comes into play, stopping Pokemon from setting up against it. It really depends on what your team needs most: a reliable physical tank or phazer.Team Options & Additional Comments >>>
Hippopotas does not have the greatest of movepools, but it has a few moves that can be useful in some situations. A Stockpile set can be used to some decent success, boosting Hippopotas's poor Special Defense to higher levels. With the abundant use of Ice- and Water-type moves, however, it may be difficult to pull it off. Curse can also be used, except that it has the same problems that Stockpile has, and it doesn't add any Special Defense boosts. Lastly, a Choice Band set with Earthquake, Crunch, Superpower, and Rock Slide might be useful, though Gligar would be better relegated to this task, due to its higher Attack and Speed.
Checks and Counters
Hippopotas's horrible Special Defense makes it vulnerable to powerful special attacks, so using strong special attackers is a good way to bring it down. Houndour and Gastly are good examples of powerful special attackers who can easily bring death upon Hippopotas with their respective STAB moves. Also, any Pokemon with super effective special attacks will instantly OHKO Hippopotas, such as Porygon's Ice Beam, Bulbasaur's Leaf Storm, and Mantyke's Hydro Pump.
Since Hippopotas is quite weak offensively and almost any Pokemon can find it very easy to set up against it without taking much damage. Gligar, who is immune to Earthquake and takes pathetic damage from other moves Hippopotas uses, can easily set up Substitute, Swords Dance, or Rock Polish and threaten to sweep Hippopotas's entire team with death-inducing Earthquakes. Krabby can easily pull off several Swords Dance or Agility boosts because of its high Defense stat, allowing it to fire off powerful Crabhammers to the opponent. The only thing that needs to be watched out for is if Hippopotas carries Roar.
Any weather changer can threaten Hippopotas with their super effective attacks and also remove the raging sandstorm. Snover, who sets up hail, Exeggcute, who sets up sun, and Mantyke, who sets up rain, can all OHKO Hippopotas with their super effective STAB attacks.