An underrated pokemon period right now is Kingdra. With the prevalence of rain offense, Kingdra can easily outspeed every threat on a rain team. In fact, it outspeeds every common scarfer in the tier under the rain. Right now, I've been using a Choice Specs set.
Kingdra @ Choice Specs
Trait: Swift Swim
EVs: 36 HP / 252 SAtk / 220 Spd
- Draco Meteor
- Dragon Pulse
- Hydro Pump
- Hidden Power [Fire]
The moveset is pretty simple. Draco Meteor does what Kingdra is meant for: wallbreaking. The usual switch in into a Kingdra is a bulky water like Slowbro, expecting a standard DD set. Draco Meteor OHKOs or 2HKOs all these bulky waters. Dragon Pulse is a more reliable STAB if Kingdra wishes to clean up teams after being weakened. Of course, Kingdra needs to deal with bulky steels like Jirachi or Heatran, so Hydro Pump is chosen as the secondary STAB. Finally, Kingdra's STABs leave it walled by Ferrothorn, which is dealt with Hidden Power [Fire]. It also lets Kingdra function better outside of rain.
For the EVs, Kingdra is given a Modest nature and max Special Attack to hit as hard as possible. 220 Speed EVs allows Kingdra to outspeed Scarf Terrakion under the rain. The rest of the EVs are dumped into HP, allowing Kingdra to tank hits and switch easily into most Politoed sets.