I think he is refering to normal mode, since he is lvl 15.
the cards you have from All Stars are not really that good... if you want to go with All Stars you need at least some of the high lvl cards: Alexei, lamar, Marina, Eyrton, lamar.
as for the other clans it really depends on what cards you have
6Sims: People do not use it? Hm. I do... even against ELO people I won with him. Many people just don't think and play some <5 power card while I have him.. and the AllStar Bonus is really devastating to medium to low power cards. (hehe).
I have an all AllStar deck too that works quite well (26/25 stars - for ELO I'll need to replace one now that Striker is lvl 4 :/. Probably Dan against Terry):
Alexei 4, Striker 4, Eyrton 5, Bhudd 3, Lewis 3, Frank 2 (still great against cards with 4 or less power and no stop bonus/stop ability), Dan 3, Flo 2.
Sidenot: Budd gets especially funny against those players with 4 level 5 cards that play a decoy (or even not) like Lost Hog in round 1 :O
Even before the ban of tanaereva and Wee Lee I've been playing All Stars in elo with very much success, as dermagus said they have really a devastating bonus for medium and low power cards, they can exploit any weakness in the opponents deck and played with skill, in my view, they are the most consistent clan for elo, with 4 high level playable cards : striker, lamar, Marina, Alexei. after the ban ulu watu's most powerfull cards I was expecting more people to play All Stars, but instead most of them returned to some "all time classics" like Sakrohm/Pussycats , Uppers/Pussycats, Uppers/Sakrohm.