well if your making a rain team you should only go with water types because then if you have the move rain it will do masive damage.for example water types usingh water type moves boost the damage and so those rain so have a water pokemon use rain then hydro pump and it will probaly be ohko.and also i recomend not to use legendaries because makes easy to win which is no fun.well only use these 2 legendaries groudon and rayqaza because they are awsome.aggron rules!
^POOR ADVICE PERIOD. Plus they're banned from OU play. ~_~
Anywho, a good revenge-killer/priority user is Scizor
Scizor @ Choice Band
Adamant
Technician
252 HP/252 Atk/ 6 Sp.Def or Speed
-Bullet Punch
-U-Turn/Bug Bite
-Superpower
-Pursuit
This guy will get a defensive boost from fire moves (it's only weakness) due to the rain. STAB Technician Bullet Punch will be doing base 80 damage (base 160 when supper-effective). U-Turn is for scouting (STAB Technician Bug Bite will hit harder than STAB X-Scizzor). Superpower is for hitting other steel-types (which resist both STABs) hard. Pursuit is for hitting the Psychic-types (particularly the Lati twins) and Ghost-types that don't have HP Fire hard when they try to switch out.