I like the classic rain dance strategy, but I'll give a few things as a caveat:
1.Thunder has 100% accuracy... both ways. Floatzal might be fast, but everyone will anticipate spamming thunder, what if the foe had an electivire, and switched in on it to activate motor drive? Don't forget that most of your pokemon will have a weakness to electric moves, and thunder with high accuracy can destroy your team if you aren't prepared.
2.Other weather teams-Pretty obvious, but you should be prepared for this.
3.Trick room, many water types like floatzal would be completely screwed in this situation.
Just throwing a few things out there, but weather is a standard set. :)