Okay so I do realize I can get away handwaving it as "GM rules" but got a question for you all.
I'm about to run a session in the next week or two where the PCs are able to get a "pet" of sorts on their side. Big strong, and stupid; monsterous humanoid. So like a Lizardfolk or Gnoll, maybe even Orc with tanked Int and Wis stats due to reasons. Barbarian or Bloodrager too so they can get the full "Bad man, SMASH" feel I'm going for. Kinda like a nice puppy you find but also can just rev it up to smash a door.
Soooooo...., how do I build this?
Do I build it as a PC? Start with one of the racial stat set ups and build from there? Take the monster entry and apply a class levels? If I do it that way, do I swap out the base entry's feats?
Again I can just say "GM reason as to why he has more feats than you while not being a fighter" or far different stats than expected. Ideas suggestions? Extra note, this is an early encounter so maybe level/CR 2-3?
Here are the rules for adding class levels for a monster: Adding Class Levels
In short, you first adjust the creature's ability scores with an array +4/+4/+2/+2/0/-2 in a way appropriate for the planned role, and then give it the class levels as if it were a PC race. That means extra HD, feats, skills, and of course, class abilities. Note that monsters that have racial HD don't get the maximum amount of hp from their first class HD.
You can certainly switch the feats, skill ranks and known spells given in the monster stat block when you're creating a unique individual from that race (with the exception of those marked with 'B', as those are the bonus feats granted to them by their race).
Alternatively, you can modify a monster by applying a Simple Class Template. It is simpler, but doesn't give much space for customization.
Another idea: Vigilante Brute archetype. Can be very funny.
HULK SMASH.