What item in Pokemon platinum alows solar beam to only take one turn?

In Pokemon Platinum, the item that allows Solar Beam to only take one turn is the Light Clay.

Here's how it works:

* Light Clay: This held item boosts the power of moves that are affected by the weather.

* Sunny Day: This move creates a sunny weather condition.

* Solar Beam: This move normally takes two turns to charge, but under sunny weather, it becomes a single-turn move.

Therefore, with Light Clay held by the Pokémon using Solar Beam, and Sunny Day in effect, Solar Beam will be able to hit in one turn, significantly boosting its effectiveness.