Here's my second go. The more I thought about it, the more it just seemed against the intent of the Alternate Power feat to have each area act as an alternate power (except in the case of the two Density forms; those really are two aspects of the same thing and should never be able to work simultaneously).
So I went with a drawback instead, which gives a good 'discount' for the complication of only being able to access one power group at a time without making the power set ridiculously cheap. The side benefit, of course, is that if I figure out I've managed to make the character unplayable with all that compartmentalizing, I could maybe start 'buying down' the drawback if / when we get more PP to decrease switching cost, or eventually eliminate it altogether as Pak grows into his abilities.
So, here's round two on the powers. I think it's a more reasonable reflection of rules intent for the power paradigm I'm working on. I'm going to start using the other points assuming this is okay, and hopefully have something later today:
[sblock=power stats]
Power disciplines: Pak can switch between disciplines as a free action 1/round
Acceleration discipline: 23 PP -3 Drawback (discipline exlusive): Total 20PP
* Flying Charge (Strike 10, limited: must move first -1/r: 5PP)
* Spectrum Flight (Flight 6 (12PP) linked: Light Control 3 (6PP)) Total: 18 PP
Density discipline: 24 PP -3 Drawback (discipline exclusive): Total 21 PP
Density (hyper-dense) (24 PP) linked:
* Immovable 1 (1PP)
* Protection 5 (Impervious +1/r) (10PP)
* Shrinking 12 (Feat: Growth strike +1, Drawback: Full Power -1) (12 PP)
AP Density (Cloud Form):
* Flight 2 (4PP)
* Insubstantial 2 (10PP)
* Obscure 4 (All visual +2/r, Flaw: Range (touch) -1/r) (4PP)
Energy discipline: 20 PP -3 Drawback (discipline exclusive): total 17PP
* Power up (Corrosion 5, Vampiric** +2/r, Distracting -2/r) (10PP)
* Power ball (Blast 10, fades -1/r) Recharge: 'vampiric' corrosion (10PP)
**'Vampiric' seemed the closest extra to my intent: namely, disintegrating something (a successful corrosion attack) recharges the blast power to some extent (I figured 1r/attack, or perhaps 1r/toughness reduction, but I'm not sure)
Gravity discipline: 23PP -3 Drawback (discipline exclusive): Total 20PP
* Hypergrav (Friction Control Increase 3) (9PP)
* Low-grav jump (Leaping 4) (4PP)
* Applied gravity (Super-Strength 5, duration Sustained -1/r) (5PP)
* Null gravity (Super-Movement Slow fall) (2PP)
* Directional gravity (Super-Movement Wall Crawling) (2PP)[/sblock]
ETA: It occurs to me, too, that since the drawback in question basically affects all powers, you might rule it a character drawback rather than a power drawback. In that case, I figure it's worth at least -4 (possibly -5) to his base PP (Very Common -3, Modest limitation -1 OR Major limitation (YMMV) -2) I'm fine with any of it, and am mostly just not entirely clear on how to properly apply drawbacks.