“Equip planeswalker” is a variant of the equip ability. “Equip planeswalker [cost]” means “[Cost]: Attach this permanent to target planeswalker you control as though that planeswalker were a creature. Activate only as a sorcery.”

Unless another effect is making that planeswalker a creature with a power and toughness, the equipped planeswalker has base power and toughness 0/0.