"Abilities, introduced in Generation III, are special attributes given to each Pokemon that can aid them in battle. Many abilities act as a 'power-up' by increasing a move or stat; others introduce a third-party effect like a weather condition. Some abilities can even hinder a Pokemon battle.
Each Pokemon can have only one ability, however, some have the option of two different abilities. The choice is random and each ability is equally likely. There are 233 'single-ability' pokemon and 260 'dual-ability' pokemon."
This is the description you get on the ability page. I think you should update to include information on dream world abilities, and have the number of single-ability, dual-ability, and tri-ability Pokemon.