First of all, the E4 are not level 60, even the champion's ace is only level 59. Most E4 Pokémon are about level 50.
You have two main options for level grinding at this point:
Option 1: Grinding on Victory Road
Victory road's wild Pokémon are all pretty close to level 40. Your team should be fine to grind against them. You can also make sure to fight every trainer in case you avoided some. It can be helpful to buy some escape ropes in case you get stuck. This is the easier option, but it is far slower than...
Option 2: Grinding on the E4
This may be harder to do, especially if your team is in the level 40s, but it is far faster than grinding on Victory road, as the E4 are higher leveled, and trainer Pokémon give more xp then wild Pokémon. This option may require some strategy, instead of just button mashing. If you choose to go with this option, here's how to pull it off:
- Make sure your xp share is turned on.
- Spend all you money on max revives, full restores, and the x-whatever items.
- Send out your strongest Pokémon first, and use some x-speeds and x-attacks/x-specials.
- Proceed to sweep that E4 member.
- Repeat until your party is strong enough that you can actually beat the E4.
Hope I helped. I would personally recommend grinding on the E4 like sumwun suggested. Either way works fine though.
