All I do is train in the Elite Four on my Sapphire game. I've already beaten it about 50 times.
Battle the Elite Four all over again, that's what I do in mostly every pkmn game
p.s. I herd that the Hoenn E4 have the most lamest moves
Surprisingly, I have 382 hall of fames already >.>
Try the Sky Pillar where you caught Rayquaza. That is an okay place to train. Or, you could try Victory Road if you became desperate enough. But Victory Road, sadly, is a pretty lame place to train once you hit the 60+ levels.
Sky Pillar isn't to bad, mind. Even so, after a while, even the Sky Pillar loses value once you hit the higher levels.
Sadly, that is one thing that has irked me continuously about the Hoenn Region. There's nowhere seriously dangerous to go, or to train. There ARE lots of places to go in Hoenn, just very few of them are actually dangerous or even strenuous.
The only truly decent place in Hoenn is the Elite Four for training up. And that gets boring pretty quickly, same thing over and over. However, it pays off, as the Elite Four hand out Decent Exp & Money. Also, Steven usually puts up a pretty decent fight as long as your levels are under the 75+ range.
wait, in emerald you cant rebattle the champion? thats kind of pointless. now i'm happy i didnt put any time into it.
There are a number of locations.
In Sky Pillar: Pokemon in the 50 zone inhabit the area. I vividly remember Claydol being there..
E4: I hate doing this because it isn't as quick as wild battles and if you decide you want to leave halfway through you can't. But hey, it harbors the Elite Four and the former Champ. So I mean...Yeah.
Battle Tower: If I am correct then yes you do gain experience here.
Battle Fronteir(E): This is only for Emerald but is very helpful for leveling up. <3
~ Star