Japanese Name: ポワルン (Powarun)
Classification: Weather Pokémon
Weight: 1.8 lbs
Gender Ratios: Male 50% – Female 50%
Base Stats: HP 70 / Atk 70 / Def 70 / SpAtk 70 / SpDef 70 / Spd 70
Castform is one Pokemon that really only saw limited light in his own generation, like Sunflora in 2nd and Victreebel in 1st. Base 70 in every single stat makes him a Pokemon that is weak even by the standards of the NU tier, not aided by a faltering movepool and STAB options determined by what kind of weather is out on the field. Castform is therefore about as chaotic as real-life weather patterns in nature, but despite his shortcomings, he definitely gets a gold sticker for effort and for sheer originality.
Castform’s stats are about as bland as an overcast sky. 70 in every stat means that Castform not only lacks any real area to shine in, but he also has a real deficiency in his ability to have his bases covered. Any powerful hit of any kind is surely going to dent Castform severely, if not outright KO him. Weak offenses also mean Castform will be relying on weather to boost up his offensive power to just over poking-with-a-pillow.
Speaking of weather, Castform will be using it frequently depending on what role he’s meant to play. Need a Fire attack? Weather Ball, Fire Blast/Flamethrower and Sunny Day. Water? Weather Ball, Hydro Pump and Rain Dance. Ice? Weather Ball, Blizzard/Ice Beam and Hail. You can also throw in Thunderbolt for additional type coverage, or Thunder for more power at the cost of greater gambling risk. Solarbeam also has some gambling potential, but watch out for a surprise switch-in that can summon Sand and end Castform. Shadow Ball and Energy Ball are some fairly solid, reliable moves, but honestly, setting up rain, sun or hail and firing off Weather Ball is probably a better plan. For support moves, other than the obligatory Toxic and Substitute, both things that other Pokemon can do better, the weather-altering moves are the only real options. Forget about Sandstorm, though – all it does is return Castform to his Normal-type standard form, and he gets no bonuses, even from Weather Ball, from whipping up that particular effect.
Castform’s ability is Forecast, which, as implied above, transforms his form and type depending on the weather. In Sun, he becomes a Fire type, while in Rain he becomes a Water type and in Hail he becomes an Ice type. During Sand and normal weather conditions, he reverts to his original Normal typing. This allows Castform to simultaneously adapt himself to improve his typing advantages and move potency while increasing the risk that he will suffer a weather shift and lose his typing advantages and move potency. Castform is a bit of a gamble to use, even in the NU tier, and with his base stats, he can’t really endure too many surprises thrown his way, so prediction and diligent use is key.
Unfortunately for Castform, he has a lot of opponents who can counter him out of sheer stat advantage. What makes Castform usable is to equip him with a Life Orb or Expert Belt and proceed to invest every last bit of energy into Speed and Special Attack and try to hammer out as much damage as possible. Castform’s only real trick is his ability to change type, so keep a sharp eye on what might be coming up that could make him lose his weather advantage and therefore his only trick. For partners, choose Pokemon that will be able to take advantage of the weather Castform will be running. For example, Hydration Alomomola comes to mind, or Snow Cloak Beartic, and even Chlorophyll Sawsbuck. Having a partner who can also run the same kind of weather-inducing move with an appropriate weather-extending item will also make supporting the team easier, since Castform will likely be using weather only for his benefit with only 4 turns to abuse it.
All in all, Castform is a bit of a rough sell, but still more usable than Luvdisc. He will most certainly test your prediction, timing, and gambling skills to their limits, but this admittedly adorable Pokemon can still bring about a bit of a shock when and if one decides to bring him along.