Well, in my opinion I think Empoleon is better because it is at a higher level and well I like water types better. :]
To elaborate on that, I would say that despite the type trump Pikachu has, Empoleon would be so much more powerful that even a Hydro Pump could have the chance to defeat Pikachu. The sheer power behind the attack would be enough.
If you're going to battle a friend with that battle set, I would suggest maybe equipping a quick claw and teaching your Pikachu thunder if it doesn't already know it. That way Pikachu has a chance to get in a thunder or two before fainting, which would cause severe damage to the Empoleon.
25 X-Seed`s
you need to level them up some more because her highest is garchomp which is lvl 66 in d/p and 62 in platinum
mewtwo lvl 100 dragonite lvl 74 empoleon lvl 58 togekiss lvl 56 and lucario and umbrion lvl 53
try to get your whole team to the same level.
level 53
Empoleon lvl66 Staraptor lvl63 Houndoom lvl64 Roserade lvl62 Weavile lvl65 Raichu lvl 63/Giratina lvl 66+ Infernape lvl66 Crobat lvl62 Floatzel lvl64/Gyarados lvl64 Roserade lvl63 Weavile lvl65 Giratina lvl66+ Torterra lvl66 Crobat lvl64 Houndoom lvl63 Lucario lvl62/Giratina lvl66+ Glailie lvl65 Floatzel lvl64
Basically, you just evolve it twice from level 53 and it will evolve. (It evolves at level 55)
on level 53
Darkrai will be Level 53
Level 53.
Venusaur learns Sloarbeam at level 53.
They are level 53 and they have 700 life points.