Do these work together?

[DeadAggressor]

If I take Monkey Grip and Oversized Two-Weapon Fighting, would I be able to wield 2 Large 1h weapons in each hand or 2 Large Light weapons in each hand?

[sonofzeal]

If I take Monkey Grip and Oversized Two-Weapon Fighting, would I be able to wield 2 Large 1h weapons in each hand or 2 Large Light weapons in each hand?
Two large one-handed weapons... but at that penalty, it probably isn't worth it. Your damage is not going to be significantly higher, but your accuracy will suffer disproportionately.

So... yes, it's possible, but not a good idea. Unless you've got something particularly clever in mind.

[Yuki Akuma]

Monkey Grip specifically doesn't allow you to wield larger weapons in your off-hand.

So... no.

[Acanous]

it would, however, allow you to wield one in your primary, with a normal in your off-hand. If the off-hand is a light weapon, you suffer less.

[Yuki Akuma]

it would, however, allow you to wield one in your primary, with a normal in your off-hand. If the off-hand is a light weapon, you suffer less.

Oversized Two-Weapon Fighting lets you wield a one-handed weapon in your off-hand while only taking the light weapon penalty.

It sucks. As does Monkey Grip. This is a very bad idea.

[Yuukale]

is there a scenario where this feat is actually optimal or is it there just to let people play with anime characters ?

[Ravens_cry]

is there a scenario where this feat is actually optimal or is it there just to let people play with anime characters ?

It's optimal when you want to play anime characters.
Still, Strongarm Bracers are better in my opinion.

[Darrin]

is there a scenario where this feat is actually optimal or is it there just to let people play with anime characters ?

Monkey Grip starts to look more worthwhile once you get your base weapon damage up above 2d8 or 4d6. After that, the extra damage from a size increase may start to outpace Power Attack.

2d8 -> 3d8 increases your average damage by 4.5

4d6 -> 6d6 increases your average damage by 7.0

You still take the -2 size penalty, but if you're only getting a x2 multiplier from Power Attack, then a -2 Power Attack penalty = +4 damage. However, if you've got a Valorous weapon, Lance + Spirited Charge, or Leap Attack cranking up the effective multiplier to x6 or x8, then Monkey Grip is still not worth it. The other advantage with Power Attack is you can turn it off or adjust the penalty as needed, while there's almost nothing in the 3.x rules to get rid of the -2 size penalty from Monkey Grip.

As always, Strongarm Bracers is the better deal, since they incur no size penalties.

[sonofzeal]

is there a scenario where this feat is actually optimal or is it there just to let people play with anime characters ?
Occasionally PCs end up with weapons whose former owners.... won't be needing them any more. Often these weapons are not what they'd ideally be using, but might be particularly effective and worth the "downgrade".

I had an Orc Barbarian using a Longsword for a while because his original weapon was only a +1 and the Longsword was a +3 with some unusual properties. Twohanding the Longsword ended up being categorically superior to the alternative.

I could easily see a situation where the PCs get some Large weapon of exceptional merit. If it's good enough that they'll likely be using it for most of the rest of the campaign, Monkey Grip could be a good idea. Strongarm Bracers are still usually better, but not everyone uses every book.