I agree with the legendary comment
It should be 3 legendaries of a similar nature (like the birds, dogs, or regis) and one uber that you can only catch after beating the elite four (like mewtwo or rayquazza)
Now, an idea I've had since I was 9......fatigue level
For instance, using moves like thrash it says "you became confused do to fatigue" correct? so why not make it an official stat.
A small bar under your health bar. The more fatigued you are, the lower your critical hit ration would be. Also, it would add a VERY interesting and difficult aspect to battling. Your pokemon could have almost all it's health left, but if it's fatigue level reaches 100, it automatically faints from exhaustion. Thus, tiring the enemy out could become a major strategy. I even planned moves like heat wave and sub zero. they would each be weak moves that only have 5 PP and deal 10 damage per turn (they are continuing moves) BUT upon use, the opponents fatigue level automatically rises by 50. however, you can only use the move once per battle.
Thus a fire pokemon, could destroy a water pokemon by fatiguing it since it has a type disadvantage and would struggle to faint it the normal way.
If your fatigue level rises above 75% you have a high chance of becoming confused. Moves like Thrash would automatically raise your fatigue by 40, and guarantee that you become confused, but the lower your fatigue level, the quicker you snap out of it.
Moves like agility, recover, and such would lower your fatigue level. Moves like Take Down would raise it.
