There is some hype behind the tag team combo of Electivire and Magmortar, and I think they could be a force to reckon with. Electivire and Magmortar have complementary attacks that, when used correctly, can deal some intense damage. But before we dive deep into the mechanics on how to use the Bash Brothers, we need to point out some cards that would be vital in a Bash Brothers deck.
First off and probably most obvious you need to use four Switches or Float Stones due to Electivire's attack doing more damage when Magmortar has energies attached to him. Since you do not wanna lose the energies attached to Magmortar, you need to retreat him when you accumulated enough energies on him for Electivire.
Secondly, a combination of Blacksmith and Ultra Ball will be an incredibly easy way to get two energy on Magmortar and another Pokemon on your bench. If you use your Ultra Ball and discard two Fire Energy you can easily reattach them to a Magmar or Magmortar without any penalty of lost Fire Energies. Along side those two cards you can also use Energy Switch to move around energy cards to deal more damage. This way is effective so you do not need to have Magmortar in your active position and can have Electivire there causing damage.
Some additional cards you can use are: Training Center, for a little more HP, Muscle Band for a little boost in damage, Dragonite EX, to move energies around in anyway you want, and Professor's Letter, so you can get out energy in a pinch.
I have explained the basic plan of attack behind this deck, being power up Magmortar while Electivire is causing havoc upon your opponent. This deck will be incredibly easy to power up and cause damage to your opponent. Magmortar can be the main attacker of this deck, but his second attack is very expensive to power up; however, when powered up Magmortar can knock out almost anything in his way.