Ah, gotta love for a file sniffer like me that the Pokemon TCG Online is a downloadable client now 
Even though it's just the Trainer Challenge, I already found a piece of nice information: the Power Relay deck. Found in the resources.assets file (make it a .txt file, open it, wait for while, and then you can search for the deck's name (Power Relay) if you wish), which is in the installation folder -> Pokemon Trading Card Game Online_Data.
I do not know its contents unfortunately except for 3 cards listed in the description (and some other cards are obvious). Unfortunately, all 3 listed main Pokemon are also the only cards the deck's description talks about. Raichu is from Next Destinies and the others are from Noble Victories, so it seems to be from multiple sets. It's also listed as a McDPromo: McDonalds? Here's the description:
Electrify your game and shock your opponents when you play the Power Relay theme deck! Foes will find themselves ferociously short-circuited when Raichu
unleashes its Slam attack and, if that doesn't blow their fuses, Haxorus will prove that lightning strikes twice with the stunning power of its Dual Chop and Giga Impact attacks. Eelektrik uses its Dynamotor Ability to find Energy and keep the current flowing, and a selection of Supporter cards ensures that your opposition won't be able to handle the static for long before the power goes out...permanently!
Perhaps in the end it turns out to be TCGO-exclusive or something (as I couldn't find anything about Power Relay for the Pokemon TCG), but for the interested I decided to post it.
Even though it's just the Trainer Challenge, I already found a piece of nice information: the Power Relay deck. Found in the resources.assets file (make it a .txt file, open it, wait for while, and then you can search for the deck's name (Power Relay) if you wish), which is in the installation folder -> Pokemon Trading Card Game Online_Data.I do not know its contents unfortunately except for 3 cards listed in the description (and some other cards are obvious). Unfortunately, all 3 listed main Pokemon are also the only cards the deck's description talks about. Raichu is from Next Destinies and the others are from Noble Victories, so it seems to be from multiple sets. It's also listed as a McDPromo: McDonalds? Here's the description:
Electrify your game and shock your opponents when you play the Power Relay theme deck! Foes will find themselves ferociously short-circuited when Raichu
unleashes its Slam attack and, if that doesn't blow their fuses, Haxorus will prove that lightning strikes twice with the stunning power of its Dual Chop and Giga Impact attacks. Eelektrik uses its Dynamotor Ability to find Energy and keep the current flowing, and a selection of Supporter cards ensures that your opposition won't be able to handle the static for long before the power goes out...permanently!
Perhaps in the end it turns out to be TCGO-exclusive or something (as I couldn't find anything about Power Relay for the Pokemon TCG), but for the interested I decided to post it.