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Route 16 (Received from Clown after showing Solrock or Solgaleo)

This move will now be unsuccessful when the weather conditions are sunny. However, in the midst of harsh sunlight, Synthesis, Morning Sun, and Moonlight will deviate from their usual effects. Instead, they will restore 2/3 (two-thirds) of the user's HP. In addition to this, Castform, owing to its Forecast Ability, and the move Weather Ball, take on the Fire type under such sunny conditions. Should a Heat Rock be held while Sunny Day is initiated, the duration of the sunny weather period extends from 5 to 8 turns. Moreover, certain Pokémon Abilities come into play during the sunshine, producing various effects: Pokémon endowed with the Chlorophyll Ability will witness their Speed doubled. Pokémon possessing the Dry Skin Ability will endure a loss of 1/8 of their maximum HP at the conclusion of each turn. Pokémon with the Flower Gift Ability will elevate the team's Attack and Special Defense stats by 50%. Cherrim, in particular, transforms into its Sunshine Form during this time, though this transformation is not exclusively tied to Flower Gift itself in Generation IV. Pokémon featuring the Solar Power Ability will experience a 50% boost in their Special Attack but will also lose 1/8 of their HP with each passing turn. Pokémon equipped with the Leaf Guard Ability become immune to non-volatile status conditions while the sun is shining. Furthermore, Sunny Day can serve as the inaugural move in a Pokémon Contest combination, augmenting the appeal points awarded when certain moves are employed in the subsequent turn. Specifically, moves like Blast Burn, Blaze Kick, Ember, Eruption, Fire Blast, Fire Punch, Fire Spin, Flame Wheel, Flamethrower, Heat Wave, Moonlight, Morning Sun, Overheat, Sacred Fire, SolarBeam, Synthesis, Weather Ball, and Will-O-Wisp will garner double the usual appeal points if used right after Sunny Day.