There needs to be a ban on impossible Pokemon and a way to filter out people asking for legendaries. You want to request a level 1 dragonite? Too bad~
In fact, there should be a way to search for people requesting a specific Pokemon. Lets say you have a Hypno you want to get rid of. You want to complete your Pokedex but aren't looking for any one particular Pokemon. You could search for people who want a Hypno and can look to see if there's a Pokemon that's being offered that catches your eye. While Wondertrade is still awesome, this gives a better sense of fairness when you don't want a bunch of Scatterbugs.
Also they need to change how the 'requested level' mechanism works. I should be able to request a Pokemon from level 30-60, not be limited to Level 30-39.