BaronessBomburst Yeah, if you don’t have the top counters with only three of you wouldn’t have been able to do it.
Thing is though, even with Tyrannitar, if the Pokemon don’t have optimal movesets tailored to defeat Alolan Marowak then they become virtually useless too. This is why movesets are so important; they can make or break a battle.
If you used your Vaporeon, it should have Water Gun/Hydro Pump, and the Tyrannitar’s you used should have been Bite/Crunch or Smack Down/Stone Edge, depending on if you have the legacy move. Last but not least (because we can discount Sudowoodo entirely; it’s useless), Houndoom should have had Snarl/Foul Play.
Those are, of course, the optimal movesets for Pokemon raiding Alolan Marowak, and not necessarily the best movesets for that Pokemon overall. Hence the importance of having several of the same high powered Pokemon (Gyarados, Tyrannitar, Dragonite etc.) with a couple of different movesets to cover as many bases as possible.
Even if all the Pokemon above that you used had the optimal movesets, you probably would still have struggled (and I think probably failed unfortunately) taking into account all the other factors too.