So, I'm pretty new to PF2E and so far I love the flexibility and ideas it brings to the table. I was never a theorycrafter and I'm also a GM for life, so Player Building in PF1E and other games were always something I usually didn't experiment much with.
I recently started playing Play by Post with Pathfinder Society rules here in the official forums, and I have some character concepts in mind that I want to see better fleshed out.
First one is a character entirely built around making the most of having a familiar. I love pet based classes and since we still don't have Summoner + Eidolon, I'll take what I can get. I like Familiars more than Animal Companions right now as they allow for more imagination and customization without having to worry about mantaining two statblocks.
Second one is a Wizard who gets the most out of Transmutation. Bonus points if I can make it work with a Familiar :P I don't yet understand how wearing armor affects magic in this system, I was thinking of an offensive oriented Transmutation character.
I'd like to know how to make this actually work, any ideas?
Transmutation Wizard with the Familiar thesis.
The thing is that Transmutation school have mostly buffs and their offensive force comes from battle forms like Dragon Form and Fiery Body.
First, ditch the idea for a familiar combatant until you have more system experience. Animal Companions w/ full development, gear (what little there is), and spell buffs will struggle! They are secondary and cannot be built to overshadow you or match a real martial PC. Buffs are more minor perks (because the game has to balance that they could go on anybody) or complete transformations into a combat form (which only work on yourself.)
And a familiar is weaker than an Animal Companion...
Though it can give you some nice perks if you can keep them alive (which is not a given as it kinda was in 3.X/PF1 if you avoided risk.)
Armor doesn't affect casting & getting armor training is simple via feats.
Except, getting better armor proficiency is hard and Dex can do most of the work nowadays. And the heavier the armor the more Str investment you need so the armor doesn't hinder you too much.
So armor's often not worthwhile for a mage.
That said, Bards, Clerics (War Priests), & Druids have armor that advances in proficiency w/ them alongside spell lists that have shifted since PF1. See if your favorite Transmutation spells made one of the non-Arcane lists. And if you want to use combat forms via Polymorph spells, a Druid is superior to a Wizard. Also, since most of your combat stats except hit points get set by the form, Con becomes a top priority (on par with Int (or Wis for Druid) if forms are your #1 tactic). That also improves your Fort save which helps against combat maneuvers. And you'll still be vulnerable because a high-Con Wizard is about a low-Con Rogue.
You probably want to double-check the Arcane list too, to make sure Transmutation still does what you like given that umpteen books that expanded the PF1 spell list have now gone away.
I don't know what you mean by "gets the most out of Transmutation" since there are several ways to interpret this.
If casting at enemies, you want 18 in your casting stat (16 if forced).
If transforming yourself to go in the front, you want 16 Con and low expectations.
If transforming yourself to do utility, you want Wis for scouting/Perception, Dex to get your Stealth up, and Cha for Deception/disguises (as well as Int enough to get the skills also needed). It may be too hard to do all of that great, but not hard to do all of it well.
If casting at allies (or self) only, no stat needed, which frees up other options.
All that to say in the end that your spell selection will make the most difference. It's like choosing feats anew every day. Full-casting is the core of the class and the class feats that support the spells you like are pretty easy to pick out of the options.
So check over that spell list.
If there are gaps where class feats are less attractive, consider a Multiclass Dedication (MCD) which can flesh out options (or even get you Wild Shape or some transmutation effect from elsewhere).