Battle Familiar and Pact of the Chain

I'm struggling with how Battle Familiar interacts with the Imp familiar from Pact of the Chain.

Battle Familiar has this sentence in it: "For the duration, your familiar can attack in addition to taking other actions as normal, and your familiar’s game statistics are replaced by the Battle Familiar stat block, but it retains its creature type, alignment, Hit Points, Hit Point Dice, and any features granted by the Find Familiar spell.  Your familiar gains a number of Temporary Hit Points equal to the Hit Points of the battle familiar."

I can't determine if stat block just means the STR, DEX, CON, etc or if this also includes it's Traits and Actions.  It's confused because Battle Familiar does use the Imp's Hit Points which are a part of the stat block.  Clearly I would like the Imp to retain it's invisibility, magic resistance, and sting but I just can't tell if these are being replaced by the Battle Familiar stat block.

How are you guys playing this?

Quote from SirBarnick >>

I'm struggling with how Battle Familiar interacts with the Imp familiar from Pact of the Chain.

Battle Familiar has this sentence in it: "For the duration, your familiar can attack in addition to taking other actions as normal, and your familiar’s game statistics are replaced by the Battle Familiar stat block, but it retains its creature type, alignment, Hit Points, Hit Point Dice, and any features granted by the Find Familiar spell.  Your familiar gains a number of Temporary Hit Points equal to the Hit Points of the battle familiar."

I can't determine if stat block just means the STR, DEX, CON, etc or if this also includes it's Traits and Actions.  It's confused because Battle Familiar does use the Imp's Hit Points which are a part of the stat block.  Clearly I would like the Imp to retain it's invisibility, magic resistance, and sting but I just can't tell if these are being replaced by the Battle Familiar stat block.

How are you guys playing this?

 

 All it's traits, saves, etc... are replaced.  That includes invisibility, magic resistance, etc...  

You retain the find familiar spell features, plus your hp and HD.  You might also keep Investment of the Chain Master abilities, talk to the DM.  But anything inherent in the form itself is lost.