There are no tiers for "official" tournaments. Tiers are something that are a fan-made creation, by Smogon & Pokemon Online, to make battling "fairer". Though, official tournaments will have banned Pokemon, e.g. Keldeo, Meloetta etc.
However, I can only assume that because you don't know about tiers, you don't do a lot of competitive battling. If this is your first time battling in doubles format, I would highly suggest you to reconsider your choices after consulting some team building articles. Double battles see moves that are not frequently used or never considered in single battles having very common usage. Additionally, a doubles team needs to have a goal, more so than a singles team does, otherwise your team will fall apart.
Additionally, as I answered on your question about Telekinesis, it's not a beneficial move, considering that you will get hit by all moves during Telekinesis is active, in addition to being not a very good move and only lasting 3 turns. There are much more useful moves Breloom could use, like Spore, Mach Punch, Bullet Seed, Swords Dance et. al that don't require any set up.
Smogon BW Articles - Double Battles
^ Read this for an introduction to doubles battling.
As for sets that are on this site, they're suggested because they work well (well most of them anyway). There are some moves that just aren't viable for a Pokemon, or are undesirable when compared with other moves and when taking into account their abilities/ stats. I would suggest you post your team on the battle subway section to get some help.
Sorry if this is stuff you already know, but since you said you didn't know about tiers, I thought it would be worthwhile to explain things.