In response to the topic title: Baton Pass passes the stat
boosts of each Pokemon onto the next one. (And it's not necessarily
only for sweeping, either.) In other words, if your Pokemon Swords Dances, its Attack gets raised by one level. Then, if you BP to another Pokemon, then that
other Pokemon will have its Attack raised by one level. Hazers and pHazers (Roarers and Whirlwinders, namely) destroy that strategy by eliminating the changes in stats you worked so hard to get (such as, in the example, the boosted Attack).
That said, as long as you've got a fast Pokemon that can last a couple of hits (hence the need for EPs in the defenses and HP), you've got a potential BPer.
If Vaporeon is used as a BPer, by the way, it would pretty much be due to Acid Armor (in conjunction with the usual Sub/BP). Yep. That's Acid Armor's a Defense-only move, but that's what it primarily passes, if anything at all.
is there really no way a bp team can counter those annoying hazers and whirlwinds?
Easy. Get rid of the Hazers/pHazers before they get rid of you. Thus, learn to recognize what could possibly be used as a Hazer/pHazer and anticipate the opponent's moves.
Of course, if you've got a Spiker, that might make your job easier by making it difficult for the opponent to switch out. Of course, that
is an emphasis on "might," and you'd better hope that your opponent doesn't have a Rapid Spinner either.