Besides the water protagonist in Pokemon HeartGold and Soul, is there any water spirit that is better than Red Gyarados? (You need to be able to catch it in one week)

The Speedy Mini Dragon, the Giant Crab (a high-WF vehicle), the Jellyfish (poisoned), and the Weather Team’s Mariuli are all good

But the BL Dragon’s Ice Fang It's very useful, 4 Peck Dragon - -

In fact, Dadu can roll to death with Explosive Beast - - (I have deep experience)