EV (Effort Values):
These are what determine which stats will go up, and by how much, when your Pokemon levels up. For a little more in depth information, try following this link:
IV (Individual Values):
These are what determine your Pokemon's base stats.
Uber is a tier that includes Pokemon deemed too powerful for OU battles. The "OU", or over-used, tier consists of Pokemon that are often used or seen in standard play.
Physical and Special Attacks:
A Pokemon's moves can only either be Physical or Special. A move's efficiency that deals physical damage like Tackle can vary due to your Pokemon's attack and the foe's Defense. A move's efficiency that deals special damage like Water Gun can vary due to your Pokemon's Special Attack and the foe's Special Defense.
Bulbapedia, Serebii, Psypokes, & myself(:
Hope this helps!