Did I brick my game at the Giant Steelix?

[Silversixx]

I have kinda just brute forced my way through the game thus far, have not caught very many pokemon at all.  I am at the part where the level 75 steelix shows up and he just wrecks my level 55 team, one shots them all.  I don't think I can leave this cave, wtf do I do?

[RyanErgo]

I played a long time ago, so maybe I am remembering incorrectly. But I used sturdy Ggravelers with moves that collapse the cavern.

 

[Silversixx]

i lost the first time really bad and overreacted and came here, beat him the 2nd time with my Noiverns move that cuts his health in half and then flamethrowered him down with my delphox.  

[Audiogoose45]

I brought a Sudowoodo with Sturdy and Counter into this fight. And... one shot later, the Steelix is down.