Well, my SD/SS (I know, not SD/EM) tanker is only 37th level, but I think I can safely give you some input on the SD side of things.
In order of powers:
Deflection: Available at level 1. Take it then. For the first few levels, there are far more mobs that have melee attacks then ranged attacks. It also provides the bread and butter in your resists - Smashing and Lethal. You're going to want to eventually six-slot this power, with three Defense Enhancements, two (or three) Resist Enhancements and one Endurance Reduction. (You'll need the End. Reduction before you get Stamina, but once you're on single-origin or IO Enhancements, the End. Reduction isn't as necessary.)
Battle Agility: Available at level 1. I took it at level 2, simple because I had the veteran power of Sands of Mu, and I didn't need another attack power at level 2. This is the ranged/AOE Defense complement to Deflection's Melee Defense. It also provides resistance to Defense Debuffs, but until later levels, there aren't a lot of these. You'll want to put at least four slots in there - 3 Defense, 1 End. Reduction (at least until you get Stamina), and maybe a fifth or sixth slots for Resistance Enhancements. YMMV, but so far, I've found it pretty easy going without worrying too much about Defense Debuffs. But as I said, I'm only level 37 with this tanker.
True Grit: Available at level 2. I took it at level 4, simply because at low levels, assuming you're not running cracked out AE missions, it's hard to find things in the level range you should be fighting that can kill you fast enough where you don't have an option to run away. This is where your elemental resists (Fire, Cold, Neg. Energy, Energy and Toxic) come from, and it grants bonus health. You want to six-slot this one, 3 Resists, 3 Health. (It's an auto-power, so you never have to worry about Endurance with this one.)
Active Defense: Available at level 6. This is where all your status resistances are (Knockback, Stun, Disorient, etc.). A tanker who is mezzed, held, whatever, can't do their job very well, can they? Now, at the very least, you always want one Recharge Reduction in here, just so it's usable as often as possible. Actually, at lower levels, or before you hit SOs or IOs, it wouldn't kill you to have two Recharge Reductions in here, switching out to one Recharge Reduction IO and one Resist IO at higher levels. (Or respec and just leave it at one Recharge IO.) With various global/IO set recharge reductions later on, it's possible to just one-slot this one and be fine.
Against all odds: Available at level 8. This is a fun power. First, it debuffs enemy damage. Then it buffs your damage. And it acts like a taunt. Unfortunately, it doesn't take any IO sets. You can get away with one-slotting this power, probably with an End. Reduction Enhancement.
Phalanx Fighting: Available at level 12. This power can be confusing to some. The way it works is like this - it provides a small Defense bonus to all positional attacks (Melee, Ranged, AOE). Then, it provides an additional Defense bonus to all those attacks for every ally (team-member) within a certain range. So, it's only somewhat useful by itself, but amazingly useful when you're teamed up, especially if you're working with a couple Scrappers or Blappers. The drawback is that if you have no team-members, you don't get any extra bonus. Plus, Defense slotting this power only affects the extra Defense from team-members. However, it is an auto-power, so you don't have to worry about slotting an End. Reduction in it. Really, the only reason to put slots in this power is to fill them up with a Defense IO set. I only have this one-slotted, as I recall.
Grant Cover: Available at level 18: I held off on taking this power for a while after it was available, simply because I solo a lot. It provides Defense (and a good bit of it), but only to team-mates, not to you. This is a very good power to have if you group a lot, and if your team-mates are not considerate about you needing to hold aggro. However, unless your team-mates are complete and utter glory hounds who have to deal all the damage and then some, you can probably get away with just one-slotting this for Endurance. As with Grant Cover, the only reason (in my opinion) to add slots to this is to fill them up with a Defense IO set.
Shield Charge: Available at level 26. This is a PBAOE. I love this power. I cannot say that enough. I. Love. This. Power. If you're not going for IO sets for this (and if you are, I suggest Scirocco's Dervish or Obliteration) then it still wouldn't hurt to six-slot this one, with your choice of Damage, End. Reduction, Accuracy, and Recharge Reduction. Standard would probably be three Damage, one Accuracy, one End Reduction, one Recharge Reduction, but YMMV. (I, of course, have five out of six pieces of Scirocco's Dervish in there.)
One with the Shield: Available at level 32. I haven't picked this one up yet, but not for lack of wanting it. This power gives you a huge bonuses to all resists (except Psionic), status effects, and it boosts your health and recovery. The crash is said to be a pain, though. Slotting this for Recharge Reduction is pointless (because it doesn't do anything for this power), so you want to slot it for Resists at the very least. It doesn't hurt to slot for Health or End Modification, though. IMAO, six-slotting it would be a waste, but four slots wouldn't be bad (two or three resists, one health).
Of all the powers, the ones that could be skipped are Phalanx Fighting and Grant Cover. Please note that I did not say that they should be skipped, merely that they could be. Frankly, Shield Defense is a very well knit power-set, and I have all of the powers in it, except for One with the Shield, and I'll almost certainly be taking that one at 38.
ok so does any1 have any suggestions on builds and powers taken?