(2) What kind of issues are you having opposing it? Examples would help analysis and suggestions.
The astral constructs just grapple and then ground and pound with full round attacks regularly outputting 50+ hps of damage per round. And at 8th level they can now fly.
Now, I realize that constructs have weak saves but still. It seems like I either have to throw in meat shields who specifically tie up the astral construct over and above anyone else or have casters target them. I can only do this if the NPCs are intelligent and/or coordinated. Last game the astral construct just about soloed a guardian naga before the rest of melee combatants could get close enough to even attack. (My PCs are largely unoptimized).
I guess I'm looking for alternate ways to tone down the effectiveness of the astral construct without my psion feeling like I'm unfairly picking on him and his tactics.
So the main issue is the grapple-monkey effect.
Option A) Freedom of Movement is a 4th level spell, it would not be unimaginable for some enemies to have access to it
Option B) Dimension Door is a 4th level spell
Option C) Martial Adepts: Swordsages can Shadow Jaunt or Stride; Warblades have stances and maneuvers that are good for grappling
Option D) For lulz, Monks. They normally suck, but they can survive.
Option E) Find monsters with high grapples for their CR (Balhannoth out of MM4)
Option F) Find monsters with odd abilities (Balhannoth out of MM4, if you are using magic-psionic transparency. Or the Summoning Ooze, for is medicine)
Option G) As you said, tactics. Dungeonscape has a few ideas, and I like them a lot.
The list goes on. It doesn't really matter what abilities he has, there are ways to shut them down. The problem is challenging the powerful character, and not wiping the rest of the party. And a Psion vs a Fighter and a Ranger might not be as bad as a Cleric in the hands of someone who knows how to use him, but the disparity is just going to get much worse as levels get higher. As I said. They got CAPed.