Play loose and fast, don´t use grapple as written, simple statblocks for unimportant NPCS and strip the implied playerentitlement from the rules!!!!
I like Olli's advice. I created an enemy for my players that had a "troublesome" quality -- if he rolled his max damage, there was one player with low HP who could be killed in a single strike. Rather than obsess about altering the stat blocks or picking a new monster, I just said to myself, "He can't roll max damage."
Lo and behold, the character with low HP (the rogue) is sent in to do some stealth recon, and the enemy (a golem) has the ability to see through invisibility, and thus wallops the rogue, and yes,
rolls max damage. I just shrugged and told the player, "You're at zero hit points, staggered, you can still take a single action." Play moved on. No death. No need to be a slave to rules and exacting perfection.
If a player asked me about an NPC's "encumbrance bracket" I would smack them upside the head for their pathetic, blatant metagaming.
Actually, I'd say this is a good reason to have more fully statted NPCs. If a player asked me about this, I'd really want to check and halt the NPCs' movement if he really were overloaded. I guess I don't mind this stuff -- if the spell is
supposed to do this, then I'd be a nice DM to actually make sure the spell has the intended effect, if indeed it works. However, I'd reserve my fallbacks. For example, if the strength drain
juuuuusst put the NPC into an encumbered bracket, I'd be very willing to say, "the NPC just dropped his backpack/shield/thing and continues attacking you at full movement."
Having said that, I would note that I'd never
tell the players what the NPCs' strength is, nor would I tell them what encumbrance load the NPC could tolerate. I'm merely suggesting that I'd let them prompt me to take a look at it for myself, and decide if the spell had done what they intended.
As a final note, I thought I'd attach what I've done in order to speed up & simplify my 3.5 edition games. I got a ton of 4x6 cards. I put a line down the middle. On one side, I list out the enemy's first few attacks. I do this because I have found that in the heat of combat, I completely forget the monster's special abilities. If I wing it, I end up playing a monster that is a few CR weaker than what is on the books, because I fail to use half the monster's capabilities. So I write down the first few attacks, at my leisure, when I have time to make sure I'm doing all the things a monster should. Then on the other side (the right side of the card) I put down what happens if the characters attack the monster. I run through a few questions -- for example, if the monster is immune to fire, then I would write, "Is the attack fire-based? Ignore it."
So when I come to the game, I have 4x6 cards for each potential enemy. If the players engage one of those enemies, I do
not look at the monster's stat block, nor do I spend time reading the module's description of the monster tactics, or whatever. Instead, I just follow step 1. Then step 2. And so on. It seems to have made some very complicated combats less overwhelming.
(Sorry about the quality of the photo of the card; I was using my iPhone, which has a terrible camera with no flash.)