[2021 Winter Revel]

Yay, I'll finally be around for one.  I guess all the breeding I'm doing to get ready for episode 19 will be worth it with all the wondertrading.

[need help battling melia v13]

Gigalith's probably the best bet among those options, assuming it has Sturdy, though I'd consider raising a Golem.  As long as it's not a complete disaster in regards to attack IVs and EVs, just slap a soft sand on it and Earthquake will do the trick.  Even in worst case scenario, it's almost a guaranteed OHKO against blade form.

[Help for Cain and Shelly in glass workstation]

Chandelure tears through both double battles in the gauntlet, especially if you pick up the TM for Psychic in the Glass Workshop, and can hold it’s own in the single battle.  Kinda frail though, so you may need a good tank and some revives handy if you don’t have another sweeper to pair with it that synchronizes well with it.  Metagross should be a solid partner for Chandelure.
 

I ran Modest on mine, 252 Sp Atk and Speed

Will o Wisp

Flamethrower

Shadow Ball

Psychic

[Pokemon Reborn good grinding spots?]

The clown at the Agate Circus is a good option, and nets you a ton of money, especially if you have the amulet coin or a lucky incense

[Where do I find a Good electric type for Amaria?]

I used Pachirisu due to Super Fang, but ultimately all you need for her team is Shedinja and either a normal type to switch back and forth between or a few revives.  It flat out walls her entire singles teams outside of Stone Edge on her Swampert, while you only have to look out for Shadow Ball on her Vaporeon in her doubles format

[Does anyone know a good way to train SpA evs?]

I know an old post from a few years ago had something about this.  Not sure if anything has changed since episode 16, but Seacrest's garden in Peridot Ward is definitely a good place to go for special attack.  

 

[Amaria's gym]

Shedinja walls pretty much her entire team