Also what y'all thoughts on
as a wallbreaker/setup mon
Prim is a very good mon with a lot of viable sets, from an AV pivot, to choice specs, to a Calm Mind setup mon. As for wallbreaking, the primary advantage Prim has flor that is anti-healing. Psychic Noise can be made Water STAB with Liquid Voice, making it a further problem for many defensive mons. You can hit many of the glue Ground type mons super effectively while also being able to hit Dark and Tera Dark mons with the anti-heals.
The main mons that counter this strat are Wellspring and the rarer Water Absorb Clodsire. Clod is easier to deal with due to how passive it is. Wellspring is the harder to deal with of the two, since it can come in and force you into a situation where something probably dies. Wellspring is also bad for slow Flip Turn pivots because it steals the momentum and provides an immediate threat. There is also the potential for Encore on Water STAB or even CM. Therefore, my advice for anybody using Flip Turn or Liquid Voice Psychic Noise as a crutch on Prim is to have a team that can deal with Waterpon. But otherwise, it is a really good mon.
My personal favorite Prim strat is Calm Mind with Psychic Noise, Draining Kiss, and Stored Power. You get Water/Fairy STAB for anti-healing/healing and Stored Power allows you to hit Clod and most other walls very hard. And even if it wind up being Tera Dark/Water Absorb, you still hit it with STAB Draining Kiss. If it is not either of those things, Psychic Noise and/or Stored Power can take it out.
Ironically, considering our prior conversation, CM Prim can be one of the better Covert Cloak mons. In addition to dumping on Garg, you tend to have an advantage against other CM setup mons. Psychic Noise would not stop you from healing with Draining Kiss, but you could likely do the same to them. There is also Darkrai. While it having Poison coverage is dangerous, you can use Tera Steel and not necesarrily need to worry about it. The cloak will prevent any hax, making Prim a fairly reliable check. Tera Steel cloak also allows you to potentially be a soft check to Kyurem without needing to worry about Freeze.
Has anyone else encountered the issue of, when attempting to build balance in this generation, the team just tends towards BO, by virtue of the threat saturation that has to be accounted for in the builder?
I'm by no means the best teambuilder, and it's likely down to an issue on my part, but I'm just curious if anyone has had a similar experience, and if so, how did you overcome it?
I have had similar problems of intended balance teams morphing to BO. Additionally, I also experienced the problem of some of my teams leaning too much towards HO. I realized that my issues primarily stemmed from what glue mons I was looking at. When I looked at mostly threats and/or used Zama too much as a crutch, my teams leaned more towards HO or at least some sort of offense. When I looked more towards building around cores of slower paced walls like Moltres, Glowking, Gliscor, or Fat Luvdisc, I was able to bring the teams back more towards balance. Another key for me was finding some walls with sustain rather than stuff like Tusk or Bolt, which while having bulk and also often working very well on balance, cannot make a long term defensive core by themselves due to lack of sustain. This isn't to say you cannot use mons like that. I often do use Tusk and Bolt as glue mons. They just cannot be the entire defensive core. A balance team needs to be able to last longer term than an offense team.
So the key for me was to make sure my defensive cores had enough sustain in them and that I wasn't just adding an offensive way to deal with everything.
Of course, you also need to add enough offense to make it a balance in more limited slots. But I find myself having grown more naturally offensive minded this gen or maybe in general. So I had to force myself to think slower paced on purpose. Perhaps other people are different. If you or anyone reading this struggles adding offense without turning the team more towards that direction, I would just encourage you do be a lot more picky about the offensive mons you do use because balance has more limited slots for everything.
has so much potential due to being able to hold an item and getting perm speed from tera. Personally, boots pivot sets with encore look promising
. I haven't seen usage stats at all but I feel that sd 
to be an issue since unaware let's you blow past with water stab and water absorb let's you boost to oblivion)
