It evolves at lv 40
but sometimes it doesn't evolve
Get a Wailmer and evolve it. It evolves into Wailord at level 45.
You cannot catch Wailord. You can, however, catch Wailmer, which evolve into Wailord starting at level 40.
Wailmer evolves at level 40 into Wailord
You evolve it from a wailmer which can be found in most water using a good or super rod.
You get wailord in route 129 or evolve your wailmer into a wailord.
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
Same time they do as in Ruby.
Evolve a wailmer at level 40.
in the hoen ocean
Wailord's moves if you evolve at level 40: lv 44:water spout lv 52:amnesia lv 59:hydro pump
Wailmer will evolve into Wailord once it reaches Level 40.
By catching a Wailmer, train it up to level 40, an it will evolve. In sapphire i think you can catch a wailord.