Umm ok, water spout fails due to his poor speed, Amnesia is easily stopped due to people using Roar/Whirlwind/Haze
Water Spout Wailord would need 252 Spd EVs, a Choice Scarf and a +Speed nature, and with max speed IVs will only be just outrunning Gengar. But things like Starmie will still outspeed you and destroy you with Thunderbolt
Rest fails on Wailord as his defences are too low to be asleep for 2 turns, so Electivire can easily switch in a massacre you (said Electivire because even if you use a Cleric to wake Wailord up, Electivire can destroy the most common clerics [Blissey, Celebi, Ampharos, Vileplume] without breaking a sweat)
Recover? I didn't even know Wailord can learn Recover