Kingdra

While Kingdra has a theoretical niche as a decent revenge killer against rain teams, it's ultimately far too inconsistent in the current metagame. Kingdra's reliance on manual rain makes it very gimmicky against non-rain teams, and it can even struggle against rain teams because it can't reliably break through Ferrothorn and hates status from other rain staples like Politoed and Tentacruel. Keldeo and Starmie are better choices, since the former has Secret Sword to break past special walls like Chansey and Ferrothorn, while Starmie has better natural Speed and Electric-type coverage for Politoed and Tentacruel, as well as Analytic to punish switch-ins. They also don't require rain to be a threat, and they are much less one-dimensional than Kingdra thanks to their better overall movepools and matchups against non-rain teams.