Raging Kronch can be declared as an attacker only if another creature is declared as an attacker at the same time. Once it’s attacking, removing the other creature won’t cause Raging Kronch to stop attacking.

If you control more than one creature that can’t attack alone, they can attack together, even if no other creatures attack.

Although Raging Kronch can’t attack alone, other attacking creatures don’t have to attack the same player or planeswalker. For example, Raging Kronch could attack an opponent and another creature could attack a planeswalker that opponent controls.

If a creature that can’t attack alone also must attack if able, its controller must attack with it and another creature if able.

In a Two-Headed Giant game, Raging Kronch can attack along with a creature controlled by your teammate, even if no other creatures you control attack.