Not sure how you would check it but yea, we used to run into that problem back in the day...lot less now that there are so many people playing the tourneys. But as I would play, I would get challenged and woudl accept. Next thing I know is I am now stuck in a game with someone deliberately taking as much time as he can between actions. Later on I found that someone of the people doing this were in clans of people I was competing with in the top 5. Not sure if they could track that, but the way we get around it is by only taking on challenges we send out, not that get challenged to us.
Just a tip if it is happening to you
The "you can't attack someone from your own guild" wouldn't work as you have already mentioned; if they wanted to cheat they would simply have friends join different guilds. I only avoid my guildmates because I don't want us to hinder each others' scores during a tournament: nothing like getting multiple members on the score card =). (That and my guild members tend to be very competitive and I have a better chance of losing to them than against a random opponent).
I like the way they've worked it and I've seen it in action where someone was eliminated from the rankings during a tournament. A perfect solution? No. But it will improve as they keep their eyes on the tournaments and the games played to see how people are trying to Buck the system.
To the administration and moderators of the game: keep up the good work - this has improved the tournament portion of the game (in my humble opinion).
Though, if there was a Sister guild, designed to support a primary guild, it would be noticeable in logs.
but at the same time, that would be only for really coordinated cheating guilds...
see... if i were to set up a Cheating Bot rig, i would only accept challenges from people who sent me a password.
the password, which i would have as No pillz ( a nice reference there) would mean that they are set in motion to win, the best way possible, so they get maximum points.
for people who don't send the password, i wait 1 minute approximately, then accept the battle, and wait 90-120 seconds approximately between actions....
but that's just a theory, i have never Cheated toward anyone specific, though, i do have an 8 5 star deck, which i use to help anybody who challenges me, by not using any pillz...(i won once while playing like this, but clearly it was because my opponent had bad luck) but as far as i kow, there is nothing illegal about throwing battles to everybody... and if there is, then i'll work on not doing it anymore .
Sister guilds seem to be more prevelant with french players, though i never got the train of thinking "your not good enough to be in the "A" guild but you can be in the "B" guild" to me it just seems to be a tered class system.
second nude you put to much thought in that cheating method for a none cheater lol
and third aren't you sweet to throw everyone a bone, but know that since saying this in this strain all the ppl that see that will challenge you in tournys lol