5th Gen Recommend me a Tank Pokemon =)

So I'm new in hear. joined specifically to ask this because Im abit stuck.

I need a new Pokemon to use as a Tank.
I would really like to try one that uses draining moves like Giga Drain, Leach Seed etc but Im not too fussed.
I just need something that can take a few hits but can also fight back abit

My Party so far is:

Raichu
Arcanine
Krookodile
Meganium (this is the one I want to replace)
Dragonite
Caracosta

so any ideas?

any more info needed will be put in this first post.

Try using this thread. You'll get better help if you ask there n_n mainly cause this section is for discussion only.