I only play on the PTCGO where Raticate is pretty easy to get a hold of due to its inclusion in the Black and White Basic Red Deck, but with the reminder that rotation's coming up, I think the loss of Hypnotoxic Laser, Mew, and Raticate itself will be enough to put me off from seriously pursuing the deck. While all of the methods you described are pretty handy, I feel like the kill needs to happen in one blow because Mew and Raticate don't have the HP to stand up to any decent threats. The Ariados due in the next set might be able to be paired with Gourgeist or Doublade for a similar combo, but until then I think that the Mewrats dream is on its last legs.