you will have to fish for it preferable with a super rod around mossdeep city. you can get the super rod from a man in a house north of mossdeep.
In Pokemon Diamond, Pearl and Platinum you can catch Wailmer on Route 223 with the Super Rod.
You cannot catch a Wailord, but you can catch a wailmer at Mossdeep with a super rod, and usually they are lvl 40-45, near or past when they evolve.
you need to go and surf by the wailmer. Go up until you see a cave. Go in it. Since your using ruby there should be 2 team aqua guards standing in ur way if you did not surf by the safari zone. Go through their base and beat the guards until they escape in a submerine. Go back out and the wailmer should be gone
you go north from where the wailmers are there are two guards talk to the one on the right find the boss and defeat him the wailmers will disappear
Wailmer evolves at Level 40.
The Pokemon Wailmer evolves into Wailord at level 40 on Pokemon Black.
Wailmer evolves at Level 40.
Evolve Wailmer
water!
The only way the Wailmer will move is that you must clear out the Team Magma Hideout north of the Wailmer. After you achieve this, the Wailmer and the man training the Wailmer will disappear.
Level 40
Level 35
Yes but its rare.
Catch a wailmer and get it to level 40.
Evolve a wailmer at level 40.
Off the east coast of Lilycove.
Wailmer evolves at level 40
you evolve it from wailmer at lvl 40 the easiest way to evolve it is to catch a wailmer with a super rod at mossdeep city