For Shelly, I generally agreed which is why 2.1 added a lot of things to try and counter her issues. Part of it is the Perma-rain which is unfortunately a necessary evil since everybody kept saying she was pitifully easy by lighting the field on fire. In E16 version, I'm actually going to give the option whether or not to fight her in Permarain and those that do get a free early Shellos. Serra will also be getting a similar treatment in order to satisfy two different wants. As for Solaris, he's an interesting case. I've had teams he's completely smoked and if I could replace something more suited for him, I would. I suppose I'll add his battle on the survey if he needs buffed.
Eh, I know that's due to how Essential AI's has been built, but I believe that some of those issues should be fixed in Episode 16...we hope. I'll describe essential's AI by saying it's like duck tape holding an airplane in the air. Reborn is able to mask it a bit better since they write AI coding in along with making some mons wipe before they do anything buggy. I do a lot of testing, but it being only me, I can only manipulate a skewed hyper offensive AI so much. The Corey buggyness I'm aware of as it's an unusual play with a special Qwilfish. Swalot...is a problem child due to an AI coding that prevents stall teams from working...at all. I did have plans on bringing a couple guys on board...unfortunately, I've only been able to one additional staff member (Solarance isn't part of the team). Once the final episode hits, that's where I'll get into permanently fixing errors instead of manipulation since AI coding won't be changed that much then. (Right now, I only do minor fixes such as Mega Sceptile's type error otherwise it'd take months for episode updates).