Frozen is an ailment that appears in usually in the Paper Mario series games. Whenvever Mario or someone else has this ailment, they are frozen for a set amount of turns and can be only healed by certain items.
The Frozen ailment is mainly caused by Ice Piranha Plants or Ice Puffs. The Crystal King's Ice Beam attack is infamous for freezing Mario for set amount of turns and when Mario is frozen, he is left wide open to attacks while only his partner can attack until he unfreezes.
The Frozen aliment is mainly caused by, once again, Ice Piranha Plants and Ice Puffs. Also, sometimes, the stage itself will fire freezing mist at Mario causing him to freeze on contact. The stage also has the chance to freeze the partner, enemies, or even certain bosses.
The Frozen ailment in this game is mainly caused by Bonechill and his army. Whenever Mario, Luigi, Peach, or Bowser are frozen, the player must shake the Wii Remote until that character breaks from the ice.
The Frozen ailment is actually only seen in the battle with Mizzter Blizzard in his Bowser's Snow Statue form. If Mario gets frozen by his Ice Breath attack, Mario cannot attack for a set amount of turns leaving himself open to attacks.