If his fairly new Dracovish was able to get a win Ash might of still won in a full battle with just his new team. Pikachu, Lucario, and Sirfetch'd are fairly strong at this point.
I am not so sure about that.
the more i watch this episode, I'm really starting to believe that Ash using dragon pokemon against her, might have very well been what got him the win in general.
First of all, he called Dragonite before the battle started, which gave Iris a chance to sense it's feelings, and thus lead to her talking to it during the match, if she cared more about victory then she could've waited until after the battle to say anything, but she didn't, and then there's her fangirl moment over Dracovish, which proceeded to catch her off guard with it's battle style, she did rebound but the damage was done, same with Dragonite learning Draco Meteor (then again she didn't see the attack coming so it's still debatable if her talk helped in that regard.)
Other type specialists in the anime like most gym leaders have shown to have massive self discipline and control when it comes to have to face what they love (even some of the crazier ones like Gardenia, who kept trying to squish any grass pokemon she came across, when it came time for battle she got serious) and then there's the battle with Olivia where she knew what was going on with Rockruff, but she choose not to say anything until after the battle was over, when she could've said something during the fight especially when Rockruff team killed Rowlet, but nope she kept her composure.
But Iris actions here, I honestly feel that if Ash had not used his dragon pokemon, he might not have won because Iris would've been more focused due to not being distracted by Ash's dragon types, because she loves the type that much.
Honestly I kind of hope Iris returns in the future and shows more discipline in battle, because if her own strength can be an Achilles heel, that that is not a good thing long term.