I would also like to point out that the majority of Showa Kaiju all have human level intelligence and Anguirus can form complete sentences, not that it matters for the fight but he's not some dumb animal.
Aside from rolling over on Steppenwolf and possibly crushing him, Anguirus isn't really equipped to fight a singular small opponent like that.. Anguirus is far to durable for Stepp to effectively injure but also way to slow and his offensive capabilities are are severely lacking when compared to other Showa Kaiju though.