Forecast (Ability ID: 59)

In-Game Description

"Changes form with the weather. Attacks when setting weather."

Extended In-Game Description (280-300 chars)

Changes form and type to match active weather. When using weather moves, automatically follows up with Weather Ball (100 power, matching type). Transforms on entry, weather changes, and turn end. Unsuppressable ability that works even under Mold Breaker effects.

Character count: 286

Detailed Mechanical Explanation

Forecast is Castform's signature ability that combines form transformation with automatic offensive follow-ups.

Core Mechanics

Form Changes Based on Weather

1. On Entry: Checks weather and transforms Castform to appropriate form
2. On Weather Change: Immediately transforms when weather changes
3. On End Turn: Checks if weather has ended and reverts form if needed

Weather-Setting Attack Trigger

When Castform uses any weather-setting move (Sunny Day, Rain Dance, Sandstorm, Hail, or Eerie Fog), Forecast triggers an automatic follow-up Weather Ball attack against the same target.

Form Transformations

Castform transforms based on active weather conditions:

• No Weather: Castform (Normal-type)
• Rain: Castform-Rainy (Water-type)
• Sun: Castform-Sunny (Fire-type)
• Sandstorm: Castform-Sandy (Rock-type)
• Hail: Castform-Snowy (Ice-type)
• Eerie Fog: Castform-Foggy (Ghost-type)

Weather Ball Follow-Up Details

• Base Power: 50 normally, doubles to 100 because weather is active
• Type Changes: Adapts to match the newly set weather
  • Rain → Water-type
  • Sun → Fire-type
  • Sandstorm → Rock-type
  • Hail → Ice-type
  • Eerie Fog → Ghost-type
• Targeting: Uses same target as the weather-setting move
• Trigger Condition: Activates through UseAttackerFollowUpMove system

Technical Implementation

• Unsuppressable: Works even under Mold Breaker effects
• Follow-up System: Uses FOLLOWUP_ALLOW_FAILED targeting
• Form Detection: Uses ShouldChangeFormHpBased weather-checking system
• Attack Trigger: Implemented via onAttacker callback

Strategic Implications

This creates a powerful synergy where setting weather not only transforms Castform but also delivers an immediate 100-power STAB attack of the matching type. The ability essentially gives Castform a "free" strong attack whenever it sets up weather conditions, making it both a weather setter and immediate threat.