Why are Uber Pokemon allowed in Smogon Doubles?

So I’ve been playing Smogon Doubles for awhile and sometimes you get nasty suprised coming your way in the form of Uber tiered Pokemon and the infamous Drizzle+Swift Swim combo. Doing some research I found only;Kyurem-WArceus (All Forms)DialgaGiratina (Both Forms)GroudonKyogreHo-OhLugiaMewtwoPalkiaRayquazaReshiramZekromXearnesYvetalAre banned from Smogon Doubles. So my question is, why are these normally powerful Pokemon (Blaziken, Excadrill, Thundrus-I and Shaymin-S to name a few) aloowed? What is the reasoning behind them being allowed in doubles but banned in singles?

Pleaselog inorregisterto add a comment.

Double Battles work differently than Single Battles.Think of it this way, where the battlefield looks like this:

Assuming Shaymin-S knows a flying move, both Azumarill and Shaymin can shift their focus onto Blaziken, KOing it and making it not become a threat.

Likewise, Blaziken and Vivillion’s Bug moves can be targeted at Shaymin-S, KOing it and making it not become a threat.

In Single Battles, Shaymin-S might not be able to KO Blaziken on his own, leading to a Speed Boost and making Blaziken become a sweeping threat.

All and all,double battles can put more focus on the “uber” Pokemon, therefore having an easier time with them.