When you want fast attacks, Bone Saw, Bonesplitter, and Taste for Mayhem come to mind
Along that, Wailord boasts the attack, Hydro Pump, which costs four Colourless Energy and has a base damage of 10+
Floodbringer Genku, Future Shaper Guardians of Oboro Katsumasa, the Animator Kotori, Pilot Prodigy Living Breakthrough Meloku the Clouded Mirror Moonbow Illusionist Moonfolk Puzzlemaker Network Disruptor Oboro Breezecaller Oboro Envoy Replication Specialist Research Thief Rooftop Saboteurs Saiba Cryptomancer Saiba Trespassers Soratami Cloudskater Soratami Mindsweeper Soratami Mirror-Guard Soratami Mirror-Mage Soratami Rainshaper Soratami Savant Soratami Seer Tameshi, Reality Architect Tamiyo, Inquisitive Student Uyo, Silent Prophet Wonderscape Sage
While its no Regrowth, you can get back a lot of key cards with it, including powerful engines like Smothering Tithe and Esper Sentinel
There's so much value concentrated in one card that it sells for more than half of a play booster box