I would definitely be using the DP Magnezone with Heatran lv X
Get the free retreat, the alternatives aren't worth it:
Magnezone (metal) IFDS - once during your turn, get a metal or lightning poke from deck
If you've got Magnezone out, you're pretty much set in that regards anyway, though it could prove useful grabbing the lv X or another Magnezone to start building up.
Magnezone (lightning) IFDS - once during your turn, get a [m] or [l] energy from your discard to 1 of your pokes, put 1 damage counter on that poke.
Irrelevant if you're using heatran anyway.
Magnezone (dp) - free retreat machine, really helps get the 2 lv X's set up quicker
Get the free retreat, the alternatives aren't worth it:
Magnezone (metal) IFDS - once during your turn, get a metal or lightning poke from deck
If you've got Magnezone out, you're pretty much set in that regards anyway, though it could prove useful grabbing the lv X or another Magnezone to start building up.
Magnezone (lightning) IFDS - once during your turn, get a [m] or [l] energy from your discard to 1 of your pokes, put 1 damage counter on that poke.
Irrelevant if you're using heatran anyway.
Magnezone (dp) - free retreat machine, really helps get the 2 lv X's set up quicker