you can, but you need a dive ball
no you cant get rayquaza
no you do not have to catch a relicanth to get a rayquaza
There are various reasons that Relicanth is hard to catch. For example, the area where it can be encountered can move.
no you cant if you want relicanth you have to beat seven gyms teach dive to one of your Pokemon and search through underwater grass it may take a while
You can catch it when you use dive.
You find relicanth underwater near sootopolis city.
You can't catch Relicanth. You have to trade from Ruby, Emerald, Sapphire or any other game that has him captured.
you find it underwater
Around sootopolis in the seaweed
on route 4
route 4
You just have to keep trying and not give up! It's all luck.... I know you will succeed!