I don't have Sumo and Salandit is abnormally ugly and I'd never even consider using it.
Dang gorl, and here I thought you didn't have good taste. 10 points to Cressingor.
I'm seriously considering hunting for a shiny Castform and making it (somehow) viable
helP me
Oops -10 points.
As for making it viable, it'd pretty much just be a weather-team filler. So you'd really only focus on it being one form, which opens the chance to deal damage with heavy hitting moves. Off the top of my head...
1) Rain Dance cuts down fire damage, but also makes Thunder 100% accurate. Sure you can use Thunder yourself, but you're also weak to it. 1HKO city, gorl. So you kind of shoot yourself in the foot with that one since you're already resistant to fire and you're now weak to electricity. It weakens recovery moves like Synthesis, Moonlight, and Morning Sun.
2) Sunny Day cuts down water damage, which you are weak to. It makes Solarbeam fire ASAP and helps out a few grass types, none of which are usually threats to a fire type anyway. Castform can learn Solarbeam, btw. It makes Thunder/Hurricane less accurate... And I think Blizzard too? It makes the recovery moves mentioned above more potent as the downside.
3) Hail can damage other Pokemon and gives Blizzard 100% accuracy. Though it doesn't provide any utility useful to Castform. The upside is it weakens weather-dependent recovery moves.
I say your best bet is Sunny Form Castform, and that also gives you more of a variety for a weather team since fire/grass Pokemon can take advantage of it. As well as any Pokemon that is x2 weak to water. And of course Pokemon with weather-dependent recovery moves.
Castform's offensive movepool is pretty decent and covers a lot of basis with just Fire/Water/Electric/Grass/Flying/Ice heavy hitters (120 BP moves or 90 BP ones, whichever). It's base stats of 70 across the board is where it truly suffers. It's just OK in everything, but OK doesn't cross the finish line. So either a Timid or Modest nature would be required to get the most out of Castform offensively. You could also try a bulky set since it does learn Cosmic Power. Maybe Left Overs + Cosmic Power spam at the beginning and just go ham. Maybe Hail Form would be best so the hail can at least damage the foes since Castform's damage won't be AMAZING enough. Though Water is the best type defensively, even with the Thunder-double-edged-sword thing going on, so maybe bulky Rain Form?
Personally I'd go for a more offensive Castform since critical hits can tear right through buffed defenses. Not to mention there's other ways to bypass buffs now. (Though do note that Castform can learn Lucky Chant to remove all chances of crits happening, so... Eh.)
