Beating Lance & Claire in Pokémon HeartGold (Elite Four)

Mamoswine: Ice Shard / Icicle Crash / Earthquake / Stone Edge
Weavile: Ice Punch / Night Slash / Low Kick / Ice Shard
Togekiss: Air Slash / Dazzling Gleam / Thunder Wave / Roost
Jolteon: Thunderbolt / Shadow Ball / Signal Beam / Volt Switch

Lance (Dragon) and Claire (Water) are Elite Four members 1 and 2 in HeartGold. Here's a battle-ready strategy:

Team Building (Level 65–70+ Recommended)

Opponent	Weaknesses	Recommended Pokémon & Moves
Lance (Dragon)	Ice (4×), Dragon, Fairy, Rock	Mamoswine: Ice Shard / Icicle Crash / Earthquake / Stone Edge Weavile: Ice Punch / Night Slash / Low Kick / Ice Shard Togekiss: Air Slash / Dazzling Gleam / Thunder Wave / Roost Jolteon: Thunderbolt / Shadow Ball / Signal Beam / Volt Switch
Claire (Water)	Electric, Grass	Jolteon: Thunderbolt / Shadow Ball / Signal Beam Sceptile: Leaf Storm / Focus Blast / Dragon Pulse / Leech Seed Electivire: Wild Charge / Ice Punch / Cross Chop / Earthquake Roserade: Leaf Storm / Sludge Bomb / Shadow Ball / Extrasensory

Lead with Ice/Electric: Lance leads with Gyarados (4× Ice weak) or Dragonite. Claire leads with Kingdra (only weak to Dragon/Fairy—use Electric/Grass).
Carry Revives & Full Restores: 10+ each. Use between battles.
Status Moves: Thunder Wave (paralyze fast dragons), Toxic (stall bulky waters).
Entry Hazards: Set Stealth Rock/Spikes earlier if possible.
Switch Smartly: Predict Dragon Claw/Outrage/Hydro Pump—switch to resist/immune.

Gyarados, Dragonite ×2, Aerodactyl, Charizard, Kingdra (rematch adds more).

Kingdra, Poliwrath, Lapras, Quagsire, Gyarados, Blastoise (rematch).

Save before each battle. If you lose, adjust team/moves and retry instantly.

Nintendo DS