Here is a set I like, although uncommon and overlooked:
Samurott @ Leftovers / Life Orb / whatever
EVs: 252 Atk / 252 HP / 4 SpD
IVs: null Speed
Concerning the Pokemon in general:
- The key is to get to do Dive at least once. It won't be super easy if your Samurott doesn't do it against a foe that fears it like Fire-type Pokemon who lack Electric/Grass-type coverage.
- Once you have landed the first Dive, use Copycat. This will make Samurott reproduce the lately used move. In this case, Dive. Unless your foe is slower than you.
- Since Dive has been used, Samurott is put into semi-invincibility position. But, Samurott with Brave and no speed IVs is fairly slow, at least slower than most of the metagame. So when you have to land the hit, your foe will move before you, missing their second hit.
And your rinse-wash-repeat this strategy.
The item choice could be anything. If you want, you could go Lefties along with two other coverage moves in case Samurott needs them / you prefer hiding your strategy to start with. Or, it could be Life Orb along with Recover / Soft-Boiled / anything for recovery. Heck, you could even turn this into some kind of setup Pokemon with Stealth Rock and Sticky Web.
EVs can be changed to match the user's goal, but 0 Speed IVs and Brave Nature along with no Speed EV at all are mandatory.
Samurott isn't even the only user of this strategy, but I preferred mentioning it because this Samurott is also legal in the AAA environment (Almost Any Ability).
Weaknesses of this strategy:
- No Guard. The key here is to be invincible all the time, but No Guard simply breaks this down.
- Wonder Guard. Dive or any 2-turns move should not be stopped from landing or else the strategy is annulled. Wonder Guard prevents you landing a non-Super Effective hit.
- A faster Copycat user, albeit uncommon.
- Water Absorb / any Ability that absorbs an Attack's typing such as Sap Sipper for SolarBeam.
- Powerful attacks. If Samurott can't use the first Dive, then it won't remotely do anything.
- Roar. Roaring Samurott out negates its plan completely, especially if it can't come back.
The list goes on actually, which makes this strategy uncommon and overlooked. However, if you provide the right support for it and have the skill to pull it off, then you should have fun with this creative idea you don't see everywhere! Remember, Samurott isn't its only user but I mentioned it because it can also reproduce this strategy legally in Almost Any Ability.