Hi R4zzb3rry_.
The standard day-to-day tournaments have a specific rule-set, this allows tournaments to be structured tactically; allowing players to use different strategies in order to win. The typical rule-set for these tournaments are:
no legends,
no Ultra Beasts,
no potions/revives,
no FEAR,
no OHKO,
no minimize and
no Full Heal.
As for the seasonal tournaments that we hold; these have a more restricted rule-set that's announced and updated on Discord frequently. If you would like to see the rules for this special tournament; please click this
link and it'll take you to the Challonge page with the rules laid out for you.