Their bonus is definitely not the largest. I, personally, consider it to be about the magnitude of Skeelz' bonus due to the fact that having multiple characters with poison is highly redundant.
This doesn't mean they aren't good though. They tend to have high power and decent abilities to make up for their bonus. I have made it to 1300 a lot of time by using them and either a half deck or a Leader and 2 splash cards. Though some weeks are harder than others with them. I usually use other clans now because it tends to be a bit easier.
Yeah... Freaks are very deadly and misunderstood.
I consider them the best bluff clan ever. Especially with releases like Baldovino where you force your opponent to pill or eat a ton of everything.
Their staples have some of the highest power and abilities as well. A look at Olga should show that. In almost any other clan, she would be staff banned. And 8/3 with SOA that reduces Power by 2? to a min 5? (GHEIST/root Olga). -2 Pwr min 5 with -10 attack min 3 and 8 Power? Totally insane.
And as people posted already, they are getting easier and easier to get past 1300 and hopefully soon, 1400. The big thing I see missing is a Spiaghi like DR because Soushee doesn't cut it at times.
And a Defeat: Poison card would be nice too.
There is a balance to the game. It is rare that you see a broken splash card having a good bonus (i.e. sphaghi). The 3 worst bonus in the game are protection ability, poison 2 min3 and -2 damage min 1. With +2 life/+2 damage, following closely. Skeelz, Freaks and Pussycats tend to get the best cards when bonus not active (my 8 card rainbow deck features Skeelz, Freaks, Pussycats, Sentinels, Montana, Junks, and a generic 8/4 [could be any clan that has one])
You can see that most of those clans are "not played" because of the weaker bonus.
Protection: Ability, maybe, but..
Poison 2, Min. 3 = Olga can become a virtual 10/9.
-2 Damage, Min. 1 = VERY good. Why do you think get such weak cards?
+2 Life = With Freaks, it's veeeery good.
+2 Damage = THKO every turn after first hit = huge mind games.
Skeelz have the best base because their bonus is the only below-average one. Cards like Chiara make Skeelz a force to be reckoned with.