I decided to give myself a bit of a challenge, so I made my team, nearly all dragon type (in Platinum). All 6 of them were lvls 53-56. Needless to say I managed to beat E4 with little problem, though Cynthia got to be a tough challenge. Because her Pokemon were a lot faster than mine, the majority of the time, she'd be able to go first. Although my Aerodactyl knew fly, and garchomp dig. So that helped. When it came to trying to take out her Garchomp, I'd loose. Only did I just manage to beat it that I had to take on her other ones (Milotic was pretty versatile against my dragon types). Needless to say, I used quite a bit of revives, of which Milotic's PP usage was going down, so it couldn't use the super effective moves anymore... lol. And then it got easier after that.