Sealeo locations — where to catch

In Hisui (Legends: Arceus)

• Hideaway Bay — Walk
• Islespy Shore — Walk

In Sinnoh (Diamond, Pearl & Platinum)

• Sea Route 226 — Surf
• Sea Route 230 — Surf

In Johto & Kanto (HeartGold & SoulSilver)

• Johto Safari Zone — Walk

Other games (5)

• Brilliant Diamond / Shining Pearl (Gen 8): Sea Route 226, Sea Route 230
• Sword / Shield — The Isle of Armor (Gen 8): Frigid Sea, Giant's Bed, Max Lair
• Omega Ruby / Alpha Sapphire (Gen 6): Shoal Cave
• Black 2 / White 2 (Gen 5): Undella Bay
• Black / White (Gen 5): Undella Bay

Sealeo — full Pokédex entry