Piplup is great.Piplup may be weak with a herbe type but it's super effective with drill peck and peck.Piplup is super effective with feu types too.As for electric types,you have to envolve piplup to learn dig.Also when toi envolve it, toi can learn herbe knot to beat water types so easily!Don't forget it can also envole to Emploen and learn hydro cannon!And don't for get metal claw either!Piplup is also very strong with it's torrent ability.Piplup is cute and when it envoles to Emploen,it looks tough and it may be too!Also,if toi had a piplup, it can learn surf and waterfall when it envoles and then toi could meet the champion!Remember,first is a bug trainer so toi can beat with flying type moves like peck ou drill peck.Next is ground which toi can use herbe knot.Third is kind of feu so Piplup can beat them easily with a water type move.Last, is a phychic type but I have no advice.Finally,the chamion's strongest pokemon is Milotic so toi can use herbe knot!