Shall we start with Monkey, since he is the weakest?
They all have the following abilities in common, usable once per round at will: become invisible, ethereal, or astral at will, shapechange, and teleport (no error).
I'd like to replace shapechange with the change shape ability.
They have ESP, comprehend languages, tongues, detect magic, and know history in effect at all times.
Most of those are obvious. Here's know history:
The know history spell, when cast, reveals the common name, background, lineage, and deeds of any item, creature, or place, should such possess any notable history at all. It does not reveal secret identities, presence of magic, magical abilities, character alignment, etc. If cast on a character, it would tell of his parents, what family he belongs to, and any famous deeds of his ancestors. When cast on an object, it reveals the specific name of the item (if it has one), any notable deeds it was used in, and the name of its maker. A katana could be revealed as the "Cloud-Cutting Sword used by the great hero Akicha Tanokura at the Battle of the Fallen Bridges, having been made for him by the master swordsmith Lei Yung." When used to reveal a creature or item that is disguised or polymorphed, the target is allowed a saving throw versus spells. If this is failed the spell operates normally. The spell has no effect on disguised or polymorphed items or places. When used on a creature, the caster must be able to see the creature in question. When used on an object, the caster must be able to handle the item. When used on a place, the caster must be standing within the grounds of the site.
They can only be hit by + 5 weapons or better.
Simplify to x/epic and/or chaotic?
They have the spell casting ability of a 29th-level wu jen and know all spells of that class.
Since wu jen isn't core, simplify to sorcerer casting (with some elemental domains thrown in)?
Once per day they can cast a cloud trapeze powerful enough to transport themselves and 1,000 other creatures.
Here's cloud trapeze:
This spell allows the wu jen to soar on a magical cloud at incredible speeds. Upon casting the spell, the wu jen gently tiffs into the air on a small cloud and then whizzes away in whatever direction he desires. The wu jen can take one human-sized creature with him for every four levels he possesses. The rate of movement is 10 miles every round. In a single turn, the wu jen can cover 100 miles! Those riding on the cloud feel none of the effects of this swift movement and the ride is perfectly steady and calm, even through the worst weather. At the end of the spell or when the wu jen decides to land, the cloud settles gently to earth and disappears.
They are able to regenerate 5 hit points per round.
Switch to fast healing, or have it overcome by chaotic weapons and spells?