Well level 50-51 are a little low when facing the 7th gym (considering that last gym leader`s froslass was at 50, my suggestion is to grind. Right where you face Noel there is a big lake, use the good rod to grind and farm Basculin. If you do not have the good rod it is in a house in spinel town, farm those for a bit and get those levels up and you should have now no problem taking out noel considering that you could get to his clefairy. Sorry if this is not much help but if you follow this you should be able to beat him good luck