That all depends on the condition. Since Tackle is weak against Steel, that's not helping. But, if you use strategies such as Baton Passing Attack Stat-increasing moves onto Patrat, more than 1HP has to be in some way, possible.
If the Steel-Type Pokemon has Defence lowers applied, than Patrat could have another way to deal some damage. Tail Whip is one way to do that, but as explained in the comments above, there's a good chance it still won't work, plus using it six times is a waste of time and the LV. 100 Steel-Type should have beaten it anyway. (LOL)
Hope this helps; remember, the answers to questions like this often is like this one - all about the conditions of the battle at the current stage.