This enemy has extremely powerful long-distance area attacks. At 100% strength magnification, it does 54,000 damage, so not many non-Uber units can survive a hit from it. Fortunately, Hackey has a very large blind spot, even larger than that of the original Tackey, only hitting between 1200-1500 range, so it's easy for fast-moving units like Awakened Bahamut and Sanada Yukimura to get in.
Overall, much of the same strategies that work against the original Tackey should also work against this enemy, but you do not want it getting a hit off on any of your important units. Also, use anti-Reds instead of anti-Blacks.
Warm the bench for team mates with his high body temperature.
Lit up the ball and calls it "demon ball"
And then throws it from far away. Its a really tough oppoent.
This enemy has very long range and a very big dead zone. Try to get your fast moving units past the dead zone and take out this burning seahorse but beware... If Hackey lands a hit on your units they'll be toast!