Because it lives in both fresh and saltwater, its best to stay clear of water in general if you want to avoid Gyarados
Vintage tournaments are unsanctioned and allow growing numbers of proxies (usually five to ten, sometimes unlimited)

Release date: 2000-10-02 Alabaster Leech Angel of Mercy Ardent Soldier Atalya, Samite Master Benalish Emissary Benalish Heralds Benalish Lancer Benalish Trapper Blinding Light Capashen Unicorn Crimson Acolyte Crusading Knight Death or Glory Dismantling Blow Divine Presence Fight or Flight Glimmering Angel Global Ruin Harsh Judgment Holy Day Liberate Obsidian Acolyte Orim's Touch Pledge of Loyalty Prison Barricade Protective Sphere Pure Reflection Rampant Elephant Razorfoot Griffin Restrain Reviving Dose Rewards of Diversity Reya Dawnbringer Rout Ruham Djinn Samite Ministration Shackles Spirit of Resistance Spirit Weaver Strength of Unity Sunscape Apprentice Sunscape Master Teferi's Care Wayfaring Giant Winnow Barrin's Unmaking Blind Seer Breaking Wave Collective Restraint Crystal Spray Disrupt Distorting Wake Dream Thrush Empress Galina Essence Leak Exclude Fact or Fiction Faerie Squadron Mana Maze Manipulate Fate Metathran Aerostat Metathran Transport Metathran Zombie Opt Phantasmal Terrain Probe Prohibit Psychic Battle Rainbow Crow Repulse Sapphire Leech Shimmering Wings

A card makes it through the test process in just three weeks
This list has a few of them, like Winding Constrictor and Pir, Imaginative Rascal, but the real focus is on 5/c spells
Being Dragons and Elementals are both relevant types that give this some extra oomph and synergies to consider if you dont want to play like I described above