Union Equip this card with a "Heavy Mech Support Platform". Not only will "Big Core" gain the 500 ATK and DEF bonus, but the platform's effect "If the monster this card is equipped to is destroyed, this card is destroyed instead" would grant "Big Core" an extra attack.
Use in conjunction with "Limiter Removal" when this card has no counters. It would be destroyed anyway, and "Limiter Removal" allows it to deal a devastating blow with its final attack.
This card only loses counters when battling a monster. Use cards like "Smashing Ground" and "Shield Crush" to get rid of your opponent's monsters and then deal direct attacks with this card, saving the counters to protect itself from bigger threats.