Alien Rope Burn posted:

Fighting vampires comes down to three things:

• Having enough M.D.C. to take all the vampire punchings and bitings you're going to take.
  
• Ability to withstand psionic powers.
  
• Ability to actually harm vampires.
  

Other than that, it's a question of how well the PCs can plan and work around vampire weaknesses. I ran a game awhile back that involved the PCs fighting vampires in South America, and vampires also just suffer from being tough as hell. Even the biggest, most ridiculous anti-vampire weapons take repeated hits to bring one down. Personally, I reduced the HP of mook vampires down to minimum (20, if I recall), so I could have scenes where PCs faced off against hordes of vampires and could actually take them down without it taking an eternity. This is especially true, I think, if you have a normal-sized play group, because Rifts seems to be "balanced" (using the term loosely) on having a group of 12-20 players crowdfunding damage against immense targets.

In any case, don't throw them up in a big fight against vampires until they're armed and prepared against them. But then, it's a one-shot, so it may be okay if they all die at certain points, depending on your intention. In your example, I'd let the dog boy have better armor than they have in the core, as well (I think they may have gotten some better armor in Coalition War Campaign or Lone Star, not sure). Having a swift vehicle to get around wouldn't hurt either. As Coalition, also bear in mind a lot depends on whether or not they have support as well.

Also, I wouldn't ever make anybody play a Coalition Grunt, but it's a one-shot, so class balance doesn't matter so much.