Yes, you go underwater of Routes 124 and 126.
NO.
it doesn't evolve in Pokemon ruby.
Tentacool, Relicanth.
No, you can not. Relicanth is not available as a wild-encounter. You may, however, trade a Relicanth with others Pokemon Games, such as Ruby, Sapphire or Emerald. Actually I have a relicanth and i found it on the news and it was on route 12 and does anyone want 2 know tell me how to unlock the locked off path on route 7
In the weeds were you can find when you dive (rare)
No only in ruby and sapphire and emerald.
Dive somewhere on the sea routes and in the grass down there you can sometimes find relicanth along with clampearl.
Relicanth is rare. They'll only appear if you go underwater on Routes 124 and 126.
Catch Clamperl, Chinchou and Relicanth most of these Pokemon hold shards
Just dive underwater and find grass where relicanth is and use sweet scent.
geodude, graveler, rhyhorn, relicanth, regirock, nosepass,
Relicanth is a Water and Rock type Pokemon that first appeared in the third generation of games. In Pokemon Ruby, it can be found underwater, although it is quite rare and will only show up one out of every twenty encounters with wild Pokemon.