Cost of Retreat
One of the most overlooked statistics of a Pokemon card is the cost of retreat. A Pokemon with no retreat cost is extrememly important because of its versatility. Free retreat Pokemon are great starters and provide high resistance to status effects such as poison and confusion, the two most powerful status effects.
Why are they good starters? Because they can buy you a round to think. Let me explain. Let's say we start with Scyther, Lapras, Pokemon Breeder, Prof. Oak, 2 Water Energy cards and Blastoise in our opening hand. The absolute best way to start the game is to lay Scyther as your active Pokemon and NO benched Pokemon. Scyther can't be killed in one round, nor can you evolve the first round, so there's no need for anything else.
What does that do and what does that achieve? If your opponent goes first, they'll have no clue as to what you have in your hand. They'll basically have to guess their attack strategy. They won't be able to use Gust Of Wind on big fat Pokemons with high retreat costs. When your turn comes, you won't have to decide your active Pokemon until AFTER you draw your card. Let's say you draw a Pokemon Trader. Perfect, trade Lapras in for a Squirtle and put him on the bench. If you draw a card that's not useful, then just play Lapras and power him up with an energy card. Free retreat Scyther and attack with Lapras as you intended to do.
Let's say your active Pokemon is Lapras and you have Scyther, Magicarp, and Blastoise on your bench. If Lapras gets knocked out, ALWAYS, ALWAYS make Scyther (Free Retreat) the new active Pokemon. You then draw your card to see if that changed your strategy. If you drew Gyrados that turn, great. Evolve him and Free Retreat your Scyther. Raindance him and Dragon Rage away. If the card didn't help, then EITHER power up Scyther so he can Slash, or let Blastoise take center stage. The point is, you get to choose without penalty AFTER you draw your card.
Poison and Confusion? If you have an active Pokemon that has Free Retreat and one on the bench with Free Retreat, you are virtually immune to Poison attacks. If your active Pokemon is hit with a poison attack, just retreat him for the other Free Retreat Pokemon on your bench. Then retreat again if you desire so that the original Pokemon is back as active. The rules state you may retreat as many times as you want during your turn.
What about Confusion? Let's say your Scyther is hit with Confusion. You should almost always attempt to retreat before you attack. Let's say you have a benched Scyther and your active Ivysaur is confused. If you have the required energy and Ivysaur is charged up, you should attempt to retreat before you attack. If successful, then make Scyther your active and you can retreat him again so that Ivysaur can attack again.
A couple of Pokemons with Free Retreat are extremely useful to a well built deck. Since I mentioned him so much, I think it's very clear that Scyther is the all around best Free Retreat Pokemon. So the next time you're building a deck, consider putting in a few Pokemon with a Free Retreat cost.