Ok whats your problem with Torterra? Just because hes fat and slow doesn't mean we dont care about it :') Infernapes storyline was recycled from *cough* Charizard *cough*.
Right, it was improved upon, so it only makes sense that Infernape would be his most important/arguably strongest pokemon in that region, especially considering the trainer that abused and abandoned him was Ash's main rival for that season.
I don't "hate" Torterra, but between seeing Ash's and Paul's I'd say that pokemon got excellent screen time, Ash's lost all the time to show that it was no where near the level of Paul's, I hope we see it in the next league if he uses reserves again, but I'm just saying, there's no reason to hate on Infernape, they made him the star of the season, get over it and move on.
Come to think of it, I'd say the only pokemon that didn't get enough screentime because of Infernape would be Torterra, all of his other pokemon did something important.
Buizel beating Floatzel
Staraptor beating Honchcrow
Gliscor being weak, going into training, coming back stronger than ever against Paul
Gible mastered Draco Meteor, and damaged a Darkrai
Pikachu...well he tied with a Latios meh
Not as big as Infernape was, but that's because he was meant to be the star.