I would like it to be higher. Especially when they use a Ground type attack on your Pidgey. I would also like their Pokemon have better movepools then just the last four moves the Pokemon could learn at that level. I would also like to see more trainers with items. And perhaps a few with Revives. The AI of the trainers at the Battle Frontier is at a good level though.
No...NO Revive capabilities. Ugh...I feel like it would be the same thing as when all those low-level Pokemon in the Battle Frontier use Protect or Detect - extremely annoying, especially when you're extremely likely to KO them on the following turn. In those cases, Protect is simply a time waster. Focus Sash and Generation 5's Sturdy ability function similarly.
If tougher Trainers were optional, then that would be a neat addition in the game for higher challenges. I personally think all in-game battle-able Trainers should be able to be rematched at high levels after the Elite 4. Strictly training at the Gym Leaders and Elite 4 can get
really boring and monotonous (moreso with the E4); giving the player a chance to travel around while still encountering high-level opponents for training would be a very welcome addition for the games.
The Battle Frontier artificial intelligence (AI) of
Emerald can be
insane at times though (apparently, they are technically cheating because they
know all your Pokemon's moves from the get-go). And this only applies to your opponents. The partner computer player's AI is some of the shoddiest I've seen. The worst example in memory to date I've encountered is when my computer partner's Tyranitar used Earthquake, which hit my Registeel for Super-Effective damage and did
0x damage to the foes due to immunities to Ground moves. -_- Battle Frontier AI in the regular overworld would be quite interesting to see in action...
I only hope I can combat the AI in the Battle Frontier/Subway facilities of Generations 4 and 5... *gulps* I've only been able to achieve a 50-win streak in Emerald
twice in all my years playing...