Storm set is filled with very good powers. Skip gale and take O2 boost as first power though if you ask me.
Thunderclap is not liked by many as it only stuns minions, but imo it's pretty good especially with you being sonic as you can stack stuns with screech and your nuke. (thunderclap right before nuke and everything except EB/AV will be stunned)
All the other powers are ranging from good to awesome and personally i'd take them all and skip gale. Maybe also sjip thunderclap, but that's to your personal liking.
Dark/sonic should be good in PvP. Excellent stacking of resis debuff, a stun, a sleep (if you take it), frightening accu debuff, good heal (with nice secondary effects), a fear power and a sweet slow patch.
It's said it's one of the 'undiscovered' gems for PvP.
Skip... gale???
HERESY!
EDIT: I think thunderclap is about the only thing you can really skip in Storm and even then it's a nice emergency power for some damage mitigation when you get detoggled and find yourself with hurricane and snow storm on cooldown and a bunch of angry mobs in your face. I respecced into it on my storm/elec because he's gone all a bit blappery lately, now that I've developed a short circuit fetish.
I think it's a wonderful set. Definately my favourite in the game. Hard to master but very rewarding.
Gale is good!
Thunderclap is a good power, the stun stacks with tornado very nicely, and in pvp it's nice to have that extra stun for people with no mez resistance...
Hurricane and freezing rain are two huge must haves! Learn the art of herdicaning.
Personally I wouldve skipped O2 Boost, but I picked it up at lvl 49 as I felt like I should have a buff....
As a stormy, your one big problem is controllers/dominators- take them down, using hurricane and anything that can mez them back.
Try this configuaration:
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Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder
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Name: Afro Storm
Level: 50
Archetype: Defender
Primary: Storm Summoning
Secondary: Sonic Blast
---------------------------------------------
01) --> O2 Boost==> Heal(1)Heal(3)Heal(3)EndRdx(43)
01) --> Shriek==> Acc(1)Dmg(37)Dmg(37)Dmg(37)EndRdx(43)
02) --> Scream==> Acc(2)Dmg(25)Dmg(34)Dmg(36)EndRdx(43)
04) --> Snow Storm==> EndRdx(4)EndRdx(5)Slow(5)Slow(50)
06) --> Steamy Mist==> EndRdx(6)EndRdx(7)DmgRes(7)DmgRes(11)DmgRes(17)
08) --> Freezing Rain==> Rechg(8)Rechg(9)Rechg(9)EndRdx(46)
10) --> Hover==> Fly(10)Fly(11)
12) --> Hurricane==> EndRdx(12)EndRdx(13)TH_DeBuf(13)TH_DeBuf(15)TH_DeBuf(17)
14) --> Fly==> Fly(14)Fly(15)
16) --> Swift==> Run(16)
18) --> Thunder Clap==> Acc(18)Acc(19)Rechg(19)Rechg(21)DisDur(21)DisDur(25)
20) --> Health==> Heal(20)Heal(40)Heal(42)
22) --> Stamina==> EndMod(22)EndMod(23)EndMod(23)
24) --> Assault==> EndRdx(24)EndRdx(29)
26) --> Tornado==> Dmg(26)Dmg(27)Dmg(27)Rechg(29)Rechg(31)EndRdx(31)
28) --> Tactics==> EndRdx(28)EndRdx(31)TH_Buf(36)TH_Buf(36)TH_Buf(46)
30) --> Amplify==> Rechg(30)Rechg(48)Rechg(48)
32) --> Lightning Storm==> Dmg(32)Dmg(33)Dmg(33)Rechg(33)Rechg(34)EndRdx(34)
35) --> Screech==> Acc(35)DisDur(48)DisDur(50)EndRdx(50)
38) --> Dreadful Wail==> Acc(38)Dmg(39)Dmg(39)Dmg(39)DisDur(40)DisDur(40)
41) --> Power Build Up==> Rechg(41)Rechg(42)Rechg(42)
44) --> Temp Invulnerability==> EndRdx(44)EndRdx(45)DmgRes(45)DmgRes(45)DmgRes(46)
47) --> Vengeance==> DefBuf(47)
49) --> Recall Friend==> Rechg(49)
---------------------------------------------
01) --> Sprint==> Empty(1)
01) --> Brawl==> Empty(1)
01) --> Vigilance==> Empty(1)
02) --> Rest==> Empty(2)
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Disco! The Godmother of all Storm/Sonics! 
Thank you very much guys.Ive been away for a few days and just got back.Im very excited about this and looks like i have got many levels of fun ahead of me.
Hiya guys im thinking about making a Storm/Sonic Defender.Im ok with the Sonic set but just need to know what the absoloute must have's in the storm set are.
I will be doing PVE and also later on a little PVP and maybe the Arena aswell.I dont really know how this will fare against opposition but we will see.
Also how well do you think Dark/Sonic will fair in the Arena enviroment if anyone has made one I will be very interested in how well this build does PVE and PVP.
Any information would be apreciated as im in the Dark so to speak about Defenders.