I pulled up Pokearth for reference while canvasing the Hoenn sea routes today, and I noticed several errors. I'm playing through Emerald, so that's the section for the corrections below.
0) Let me mention one thing first, a nitpick, really. Pokearth calls "Cool Trainers" just so, by two words, but the game shoves it together as one word (all caps). I realize that the latter is probably a consequence of naming restrictions in the game, but I'm a bit of a perfectionist, so I had to mention it, just in case you weren't aware of the difference.
1) Swimmer Dean on
Route 126 is missing from the Emerald section; his pokemon are the same as his listing in the RuSa section, but I'm not sure about (wasn't paying attention to) their levels.
2) Triathlete Donny on
Route 127 is female.
3) Triathlete Allison on
Route 129 and Triathlete Taila on
Route 131 should be
swimming triathletes, not
running triathletes.
Route 132
4) Swimmer Linda seems to have been misplaced: she should be on
Route 133.
5) Expert Paxton's pokemon are level 33, not 34.
6) CoolTrainer Darcy is female.
7) There's no mention of the Protein found in a pokeball below (west of, rather) CoolTrainer Jonathon.
Route 134
8) CoolTrainer Marley and Swimmer Laurel are female.
9) Swimmer Jack's Gyarados is level 34, not 33.
10) Sailor Hudson and his level 34 Wailmer are missing from the trainer list.
There's one other thing, which might be a mistake or it might be intentional. Trainers (at least that I saw) whom you can rematch have a note that says "Match Call Rematch" in every instance they're listed. When I first saw these trainers, I tried to find one that didn't have this note, the first match (not a rematch). Having figured out that the first instance is the first match, it's easy enough to read now, but I still think it would be best to distinguish the first match from rematches so that future visitors aren't confused like I was.