during the tournament, your rank is based on the number of battle points you have received in comparison to the number of players, and the amount of battle points they have received.
which means in a tournament, where there are 1270 players, you start at 0 battle points, which is not calculated into any rank at all. but once you have recieved battle points while in a tournament room, you go up in the rankings...
but... save for ELO mode, your Daily, Monthly, weekly, and overall rankings don't matter in a tournament.
these Rankings are calculated by the number of over all battle points you have received, both in and out of tournaments, and in every room. the Rankings here are only active if you battle during the ranking period.
in ELO, your ELO score decides where you fall in the ELO rankings, since ELO value goes back to 1000 every week, it's different from other rankings.
then again, i could be completely missing the target with this answer...