I'm not sure if you got a coherent explanation so in any case, here's the low-down.
There are two types of level balance, level 30 open and level 50 All. You unlock level 50 All Colosseum battles by beating all of the inital Colosseum battles, which are set at the default level 30 Open. You can beat the Colosseums multiple times, and they get harder every rank.
Level 30 Open means basically that all of your opponent's pokemon will be set to the level of your highest pokemon. If your pokemon are all below 30, the opponent will still be a 30, though.
Level 50 All means that all of the pokemon in battle will be set to level 50.
All Wifi battles are level 50 all.