with the choice band and choice specs etc. those movesets are great! but, can you switch in the battle tower for the sinnoh region?
i dont kno much so can someone tell me about it and its rules.

You can hold items in the Battle Tower but you cannot switch between them while your playing. After or before you can switch, but not during.

so you r saying i cant switch pokemon during the battle?

O, I thought you meant items. You can only choose 3 pokemon for Single battles and 4 for Double battles. You can switch between the ones you've chosen and only those. If you lose or win 7 in a row, you will exit the tower. When you reenter you can switch the 3 (or 4) you chose. Does that answer your question?

so while im battling in the battle tower and im battling someone i could have a salamence and switch to dragonite in the middle of the battle ?

Yes, provided you chose them at the beginning. It works just like any normal multiplayer battle would. You can switch mid-match but it won't tell you ahead of time what the foe is using next. For example lets say you do a single battle and chose Salamance, Dragonite, Pidgey for your 3.

Battle 1
you: start w/salamance since he was chosen first
them: throw out bulbasaur
you: switch to pidgey
pidgey KO's bulbasaur
**No message saying who is being used next**
them: throw out charizard
you: switch to dragonite
charizard uses flamethrower
dragonite enters and takes the damage
dragonite vs charizard

in between battles you heal and your salamance will always be first

o so you can switch, thanks