Synthesize - This one, though, is fine. It's basically Rain Dish for the sun.
Solar Flare - Yeah, okay. It's Flamethrower with more burn chance and less power.
Extraction - A Grass-type Water Sport, but this actually could see some use. Water Sport is given to Pokémon who are already resistant to Fire-type moves.
Petal Defense - Strictly worse than Cotton Guard, but I guess it could be an alternative for flower-like Pokémon.
Scald - The move change seems too cookie-cutter to Solar Flare, but that's just my opinion.
Frosticle - 80 power is much too powerful for a 30% freeze. Freeze is the single most powerful non-volatile status condition, and therefore needs to have a much lower freeze chance for that base power.
By the way, Discharge and Lava Plume can hit multiple Pokémon in Triples and Doubles, whereas Frosticle and Mind Bubble can't. Scald is also not of the type that its accompanying status condition is.