How do trainers work?

[Staf]

So from what I can tell, you can play fossils during setup, but no trainers/stadiums/supporters/tools during the first turn. Trainers you can play as many as you want during a turn. Stadiums stay in effect until another stadium is played or a card gets rid of it. Supports you can play one a turn, but other than that they are just like trainers. Tool you attach to Pokemon and they stay attached until the Pokemon is knocked out. Do I have everything covered and correct?

Also what is the best way to shuffle your deck? I don't want to bend the cards like I would normal playing cards.

 

[PokePop]

Yep, you pretty much got it.
Although, some Tools get discarded after a turn or so. Check their text for these exceptions.

I shuffle unsleeved cards like any deck of cards.
Sleeved cards I shuffle side to side instead of end to end to prevent the sleeves getting ripped.

Just don't bend them so much. I never have a problem with the cards getting damaged.