While Lanturn can have a nice Electric immunity with Volt Absorb, and gets solid moves in Surf, Thunderbolt, Ice Beam, and Dazzling Gleam, ultimately Barraskewda is usually the better choice.
Barraskewda's stats have been completely min-maxed, making it a fast, frail and deadly physical attacker. With Liquidation, Crunch, Close Combat, Psychic Fangs, and Drill Run, it has a wide array of coverage moves that it can use to OHKO many opponents in the game. While Lanturn is far superior in the HP department, it's slower and less offensive than Barraskewda, making it an inferior choice -- who needs HP when you outspeed and OHKO most Pokemon anyways?
Lanturn does win out in HP, and debatably Ability if it doesn't have Illuminate. STAB Electric moves are also helpful, but typically, Barraskewda's able to do just fine without them. Arrokuda also evolves earlier than Chinchou, albeit just one level before.
All this contributes to making Barraskewda the preferred choice. Its Attack, Speed, and movepool are all better than Lanturn's, and in a game of hyper offense, that's what really matters. Here's a set:
Barraskewda @ Muscle Band / Mystic Water
Ability: Swift Swim
- Drill Run
- Crunch / Close Combat
- Poison Jab / Close Combat