Where do you get a tropius?
You have to go to pastoria and head south. you have to look in the bushes and look for a man. talk to him and he will tell you to go to veilstone in the ruins. on the way up you have to cath three ghastley's. continue to the top until you find another man. talk to him and he will fight you for his tropius. to win you have to have a lv. 54 waillord, a lv. 67 Infernape, lv.98 Lugia, and of course the three ghastley's. if you win he will say sorry and leave. next the tropius will fly away. Then you have to travel to Lava Ridge and travel south until you get to an old ladies house. you stay and rest until morning. you wake up and talk to her and she says that her husband went out in a storm and disappeared. Then you have to go out in a storm and find her husband. You end up finding that tropius and her husband are lovers and they give each other bj.
After you get the National Dex, Tropius can be found in Pastoria City's Great Marsh. Tropius will only appear on certain days (i.e. some days it will be impossible to find them). You can use the binoculars in the upstairs room of the Great Marsh entrance building to see whether they are available (100 Pokemon dollars per look)