Hey there.
Let me first tell you that when it comes to battling, you are not alone. Battles are a real pain in the tail for me to write, which may sound strange considering that I'm writing a journeyfic, but still. I'll tell you first that if you want to have a battle, decide on which mechanics you're using. For example, do you want your battles to be turn-based strategic duels, or should the Pokémon be sicced on each other like in a dogfight? Personally, I use the turn-based method, but as others pointed out that is
not the entire script of the battle. Don't just say something like...
"Charmander!" called Alec. "Use Scratch!" Charmander ran towards Ratatta and raked a claw down its side.
"Argh!" boomed Bart. "You'll pay for that! Ratatta, give it your best Tackle!" Ratatta slammed into Charmander's underbelly with its head. Charmander fainted.
"Oh no!" wailed Alec. "I have been defeated!"
Well, by all definitions it got the point across, but it was... well...
boring. Add the Trainer's (or Trainers') thoughts, put more description into the Pokémon's actions or the Trainer's, and please, please don't think that a one-on-one battle between a Charmander and a Ratatta should be about as long as the average Stephenie Meyer novel.
Otherwise, yeah. Like the others said, we need some examples if we want to identify things more in-depth.