ok,what we have BTG already,why we need BTCP?

BTCP is a new direction for the dev team of ZClassic.
But it's a brand new coin, no mining pools, no exchanges supported.
Mining pools will be up after mainnet launch at 2nd of march. A lot of miners will swap to BTCP instantly. Suprnova has already announced BTCP support and there are a lot of equihash fire power waiting.
Exchanges supporting BTCP are TradeSatoshi, KUCOIN and HitBTC. I think there will be more exchanges supporting BTCP in a few weeks, but cannot see the future so can't make a promise.