Piplup is great.Piplup may be weak with a nyasi type but it's super effective with drill peck and peck.Piplup is super effective with moto types too.As for electric types,you have to envolve piplup to learn dig.Also when wewe envolve it, wewe can learn nyasi 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 wewe had a piplup, it can learn surf and waterfall when it envoles and then wewe could meet the champion!Remember,first is a bug trainer so wewe can beat with flying type moves like peck au drill peck.Next is ground which wewe can use nyasi knot.Third is kind of moto 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 wewe can use nyasi knot!