Spray can get kind of goofy if your players get lucky, or creative with their use of Awesome x2 and Gnarly and/or Burn. This can be solved by having Spray only allowing the inclusion of one extra match in your attack per rank. This is one of the Extra tweaks they included in Bigger Bads.
It can also be a bit ridiculous if you buy multiple ranks of something like Tough or Gnarly. It's fairly easy to have a part on your Monster that has at least 5 dice in both of these and Awesome x2 and still have 3 dice in your pool. That part will get wiped out easily if you ever manage to actually do damage to it, but it would have enough Tough to be effectively invincible, and enough Gnarly to wipe out something in a few hits. I haven't seen any players of mine take advantage of this because it's honestly a bit of a boring option, and it can easily be countered by using a Useful power that can Paralyze or Stun, or even a simple Defends location.
Other than that, it's largely up to what creative uses players can come up with for their Useful powers. A clever use of one of these can get past a lot of roadblocks in unexpected ways, considering there's no given limits to their capabilities.
Thanks for the heads up. This will be very helpful.
The thing I discovered from running Mrs Frieda's Halfway Home is that even though it's really easy to make a powerful, using your monster should always cause more problems than it solves. Things ranging from getting in trouble with your parents to you one day noticing that there are strange men in black suits and mirror shades checking out your rose bushes.
I'm really going to try and utilize the MIB if they go nuts. Would it be wrong for them to show up with a kid of their own or even a whole strike team should the player choose to have their monster go apeshit? I think that is a perfectly exceptable response.