This might be the problem:
>This is very rare but if your Pokémon have perfect IV stat and it is noticed by the Random Matchup then you are also prohibited from battling for a while.
( The perfect IV is usually still overlooked but in suspicious actions you can get disabled for a few days to a week)
This is the only thing that could occur without it being illegal, if you say you obtained and trained them legally.
It might be a good idea to post your party and its' movesets to let us see what might be the problem, but if all of them were 100% legal that should only really be the problem. According to the source, items banned include Soul Dew on the Eon Twins.
And irrelevant to the subject, the pentagon isn't the most trustworthy legality checker. From what I've read it means it just came from your game's region, if it came from another game the pentagon wouldn't be there.
Hope I helped. :)