"WE HAVE A SEVERE CLAUSE ABOUT SWITCHING AND LEGENDARIES. Neither is allowed to switch without the aid of a switching move such as Baton Pass or U-Turn."
That's a terrible rule. Trick Scarf will let you setup as much as you like. Starmie doesn't have BP/U-turn so yeah.
Lead:
[email protected] Trick/U-turn/2 filler
The rest of your team can consist of Pokemon that can set up on whatever Starmie is locked into (Water Absorbers for Surf/Hydro Pump, Volt Absorbers for Tbolt, Dark-types for Psychic, light Pokemon for Grass Knot).
Espeon can be useful too since it has high Sp Def, and learns Baton Pass.