Nope yanmega forces you to use up like 5 or 6 spots that are used for deck disruption, it's also destroys the consistence of the deck as terrakion is rarely ever ohkod first turn, and you can get a bad start with yanma and will make you have to play to get the same number of cards in hand which you don't have to do without him.
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Since when is a free retreat basic a bad start?
Just wondering, why is there no pluspower in this deck?
No space or is it not needed?