Played my first game with the Kraken last night vs my buddy's trolls and his Mtn King.
Now what I'm about to suggest is probably going to ruin the friendships you have with your gamer buddy's. Or at the very least, cause lots of complaints and whining. You may also have a hard time finding people to play against if you do this all the time.
It'll cost you 8 pts out of your total, but it'll be well worth it as you'll not only be able to completely remove your opponents colossal, but also his next big heavy hitter.
Simply take 2 Pistol Wraiths and Gorman.
Thanks to the PW's death chill ability and the dismal def of colossals, you can simply camp your PW 10" away from any colossal and repeatedly shoot them so they must forfeit both action and movement each turn.
[EDIT: Sorry, Death Chill doesn't stack. So 1 PW is all you need with Gorman. But a 2nd PW would make a great backup plan]
Use Gorman to blind your opponents next big heavy hitter and you should be able to walk all over everything.
Of course, you need to protect Gorman and the PW's, but that's what McThralls are for.