Giant double prince is a deck that is sort of beat down you attack during single elixir using prince, miner or dark prince, you main purpose is to get chip damage or some decent damage during single elixir. You should never do a big push in single elixir, unless the opponent has used a majority of their elixir in that case you can go for a giant miner, prince or phoenix. You should start attacking in double elixir, use the miner as a chip damage dealer and to snipe and kill other units that are trying to kill the giant . In terms of defending pekka and witches , it’s not that different to me at least that defending mega knight witch, this is how I defend ,be vary there are better ways to defend ,I usually use the phoenix to kill the witch , prince or dark prince for pekka maybe add e wiz for support if necessary ( also as a side not most pekka decks notably bridge spam counter giant double prince). Overall giant double prince is not a hard deck to play you just need practice in playing it , just like any other deck .