One of the most common and best trainer cards that are out there is Item Finder. It can be a Oak, Energy Removal, Bill, Nighly Garbage Run or a PlusPower. It could be any Trainer in you discard! It's good to restore your trainers back to your hand.

Discarding

Discarding 3 cards for 1 can be a bad thing. Two other cards from your hand. For example, say you got a lonely Scyther as a Basic and you have to Oak. Your hand is a Wigglytuff, Clefable, Professor Oak and Item Finder. You could Item Finder a Nighlty Garbage run shuffling the Wigglytuff, Clefable and another card of your choice back in your deck! Then you can Oak without discarding them.

Drawbacks

Discarding two cards is most of the time a drawback. It also can be very annoying getting two or three of these in a opening hand too. But thats about the worst it gets.

I think Item Finder will always and should always be used in decks. Maybe 1 or 2 even in decks with STS rules. I give it a 9.0. I give it a 9 because you have to discard two cards. But it also can become in trainer thats in your discard.