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The issue was that your name had Вќ input before it. I'm guessing that you initially wrote in a different language set by mistake, but the old client doesn't show these letters, despite registering them. Here's my result after writing in БГ from Cyrillic: Anyway, here's your save file with the name fixed.

Would you mind sharing your save file? I'd like to look into this.

At the moment your best choice would be Lava Plume.

I recommend swapping out your Serperior for a Lycanroc with Rock Slide and Accelrock. Use it to counteract Minior and Noivern and the rest should be easy pickings for Vaporeon and Camerupt; though I'd suggest swapping out Eruption for something else, unless you're using a Quick Claw.

Drizzile.

There's very few things that Toxicroak outspeeds, so keeping it Adamant and giving it a Choice Scarf later on is my own plan; so far Adamant has pulled through without issue. Lycanroc Midday I'd say is better off as Adamant until you get Swords Dance, at which point Jolly would be the optimal choice. For Flygon either Jolly or Adamant would work, since it depends on how safely you can set up with Dragon Dance.

Get a Cloyster with Shell Smash and put a Chople Berry on it. If you don't have one, fish one up from Celestinine Mountain with a Super Rod.

Inteleon.

Generally and specifically for this lineup a dual screens and mimic Mr. Mime would be more useful; mimic generally being there to abuse certain moves & field effects. Musharna's purpose at this point would be to put things to sleep, which if combined with Moonlight and Psychic could prove useful, but moreso if you plan on using mons like Sawk later on, as the sleep will allow them to set up (Bulk Up, etc.).

5 wins against elites nets you a Deino egg after a short quest involving Garret. None that I've found. Currently I believe only the hiker and Alistair are available; the closest thing to a 'choice' vendor being the Undercity one. Green guy on the northwest of Cellia Central is looking for his key; inside is a Gligar (LV 42). If you mean the building near the truck, where Tommy is causing a scene, then no - there's no sidequest yet. No, the most northeast house has no map connected to it.