While its frailty might indicate Bulk Up won't help Floatzel much at all, it has the tools it needs to make this work. Bulk Up not only raises Floatzel's respectable Attack, but also beefs up its Defense so that it can take physical hits better, which is important for this set to function. Baton Pass is also vital to Bulk Up Floatzel's success, allowing it to bestow its boosts to a fellow sweeper to initiate a sweep or just get away from danger without losing momentum. Waterfall is Floatzel's STAB move of choice, as it is a very reliable move. Floatzel also holds the distinction of being the only fully evolved Pokemon in NU that can Baton Pass Bulk Ups, so it can help out a variety of physical sweepers that either cannot boost for themselves or appreciate the Defense boost to prolong their rampage. Floatzel also has access to Taunt, which is incredibly useful to prevent status, phazing, healing, or opposing setup sweepers. The main selling point of Taunt is how it turns the tables on bulky Water-types that would severely wall Floatzel otherwise, notably defensive Seismitoad with Scald, Earthquake, and Toxic, meaning Bulk Up Floatzel can actually lure in opponents for it to set up on. Other Pokemon such as Wartortle, Alomomola, Misdreavus, and Torkoal are easy targets to start setting up Bulk Up on and pass the boosts. Note that Floatzel can take a good deal of damage from the likes of Scolipede's Megahorn even with Bulk Up boosts, which is usually your cue to pass the boost to a teammate that can handle the threat better.
With max HP investment and a respectable base HP, Floatzel can set up Bulk Up on foes such as Samurott, Scolipede, Piloswine, and Kangaskhan with health to spare. Bulk Up makes up for the lack of Attack investment, as Floatzel reaches 370 Attack after just one boost, the equivalent of fully invested positive-natured base 119 Pokemon. Leftovers allow Floatzel to accumulate more boosts, though it's usually not more than two. However, pinch Berries, notably Salac Berry, can be used to grant an additional boost for teammates to receive, though Floatzel would be near dead if it does pass the berry boost. Water Veil has significant use on this set, as it prevents Scald and Lava Plume burns, further easing its setup. Obviously, teammates that appreciate the boosts are welcome. Scolipede and Drifblim resist Grass for Floatzel, and can even use Baton Pass as a way to backup Floatzel in case they encounter roadblocks such as Torkoal and Misdreavus, which can burn them; Golurk takes Electric-type attacks for Floatzel, and hurts things even more while being harder to bring down with physical attacks if passed to, and even stacks boosts with Rock Polish. In terms of defensive synergy, Grass-types are still there; Grass-types that can take advantage of the Bulk Up boosts, such as Swords Dance Jumpluff, Rock Polish Torterra, and Sawsbuck, are excellent partners. Sweeping with Floatzel itself is a perfectly viable option, though you'll need to sacrifice its great utility in Taunt. The usual EV spread of 4 HP / 252 Atk / 252 Spe is best for optimum sweeping but leaves Floatzel too frail to set up more than one Bulk Up most of the time. Return offers great neutral coverage alongside Waterfall with very few Pokemon resisting both; Ice Punch can hit Grass- and Dragon-types hard at the cost of being walled by Water-types, though with Baton Pass, this is less of an issue. Note that even with Taunt, moves such as Dragon Tail, Circle Throw, and Clear Smog can still remove the boosts, so a powerful offensive partner, such as Golurk, Jynx, or Sawk, should generally be used to quickly dispatch these threats.