His initiative modifier is +12, so he pretty much automatically knocks out a powerful enemy at the beginning of combat. Knocked out = defeated, with the Coup de Grace rules, or just cutting him up enough.
Really that depends on the encounter.
Against any single CR 6 creature he'll probably win initiative, if there are multiple groups of enemies including some quick ones it's not certain that they'll all act after him and what happens before he acts could impact heavily on what he can do.
if he can detect which are the powerful creatures and if he can get there as a move action then he gets one sneak attack action in on the first round (he's a lot more effective if there's an actual surprise round that the party has achieved but that's not overly common in general)
And yes, he has god stats. Every character he makes gad god stats. I've never seen anything less than a 13 on his character sheets, and never less than two 18s. He decides on whatever stats he wants. I wouldn't mind if he was SAD, but because he's MAD, all those modifiers add up in a crazy way.
If that's the situation then the GM should point either
a) query the stats under point buy or
b) insist that all character stats are rolled while he is watching.
Given those sort of stat arrays damned near any class will get a huge increase in power or survivability.
I'm fairly certain that being grappled means you are flat-footed to every other creature not in a grapple with you. If I'm wrong, then that's another rule manipulation he pulled. Either way, I'm fairly certain that he's finding ways of making opponents flat-footed to him on a regular basis, if not all of the time.
from
Conditions - Pathfinder_OGC
Flat-Footed
A character who has not yet acted during a combat is flat-footed, unable to react normally to the situation. A flat-footed character loses his Dexterity bonus to AC and Combat Maneuver Defense (CMD) (if any) and cannot make attacks of opportunity, unless he has the Combat Reflexes feat or Uncanny Dodge class ability.
Characters with Uncanny Dodge retain their Dexterity bonus to their AC and can make attacks of opportunity before they have acted in the first round of combat.
Grappled
A grappled creature is restrained by a creature, trap, or effect. Grappled creatures cannot move and take a –4 penalty to Dexterity. a grappled creature takes a –2 penalty on all attack rolls and combat maneuver checks, except those made to grapple or escape a grapple. In addition, grappled creatures can take no action that requires two hands to perform. A grappled character who attempts to cast a spell must make a concentration check (DC 10 + grappler's CMB + spell level), or lose the spell. Grappled creatures cannot make attacks of opportunity.
so no (although it's an understandable mistake because I believe it did in D&D)
Check the methods he's using to get enemies flat-footed and see if they actually work under the rules. If they don't mention it to the GM in private.
Note that flat footed is a condition, not just denied dex to AC so it has to be specifically stated as being flat-footed to get all of the feats to work for this character
Oh, and his damage is 1d6+3 plus 3d6 sneak attack (item for +1 die of sneak attack), plus he adds another 9 to that, so he does 4d6+12, for an average of 26 damage. Higher than your fighter, I believe.
it's 2 points more damage compared to the very unoptimized fighter where the character can get sneak attack and all of the other feats applying - which should be rare.
However the fighter has a lot more feats available to pump damage if desired and hits more often.
Also the fighter does full damage to all monster types that the rogue will while sneak attack and non-lethal damage can mean that various enemies are immune to the rogue.
In addition, he will deal far more damage at higher levels than the Fighter can do. Because of the increased die of damage, at level 11 he's doing 1d6+3 normal damage, and another 10d6+30 from the sneak attack. Oh, and I totally see him taking the feat that allows rerolling 1s on sneak attack damage dice, which again increases his average damage.
a) only if he keeps advancing rogue rather than monk which may not be ideal
b) off the top of my head that feat will add around .5 damage per sneak attack dice so not a huge increase in damage.
c) his attack bonus is going to be down on a full BAB class.
and he'll be doing basically no damage to undead, constructs, oozes or anything with concealment (some of which might be avoidable with feats)
The difference between your fighter and his character is, I don't know, about 6 skill points per level, a ton of class skills, rogue talents, trapfinding, uncanny dodge, trap sense, and evasion. All the fighter gets is saves against fear, and a better to hit bonus. Out of combat, the rogue can do so much more than a fighter can.
You're missing fighter bonus feats, normal movement in heavy armour, Armour training etc from the list of differences as well as hit points and BAB.
Also note that the character loses flurry of blows if he wears any armour which means that his AC will be a fair way behind the fighter...
Rogues are better out of combat and at skill use than fighters, hardly a surprise. However as you level up that becomes much less important when magic is around.
And the general impression I have is that rogue talents aren't that hot.
When it comes to power, I think his rogue far surpasses other fighters. I'm not going to argue about it any more. Sure, if his attack only worked once, maybe it'd be fine. However, he has been able to pull of multiple strikes per fight, making him far more powerful.
10 to 1 he's wrong in how he's doing it.
Honestly, at this point I'm just unhappy that he decided to use Ultimate Combat, a book that the DM was not letting him access. It's just like in my game, I said no Book of Exalted Deed or Vile Darkness, and no fan-made content, and yet he played a character with both, refusing to change or admit he violated my rules.
If you were playing with him, I think you might see things differently, StreamOfTheSky.
that's a different factor from the character he has built being overpowered
a 3.5 D&D fighter with VOP wouldn't have been allowed in your campaign but wouldn't be overpowered.
If the character he's designed is played correctly under the rules it will probably not be overpowered in combat (I've seen some discussion on feat combos that will allow the feats to be used on many attacks but it's not going to be an option for quite a while)