Activate the following cheats by entering the corresponding codes at "Features" > "Codes":

CHEAT FUNCTION - CHEAT CODE
ABA ball - payrespect
2K Sports team - 2ksports
2k China team - 2kchina
NBA2K development team - nba2k
VC squad - vcteam
Bobcats Nascar Racing uniform - agsntrccai
Cavs Cavfanatic uniform - aifnaatccv
Hardwood Classics uniforms - wasshcicsl
Hornets Mardi Gras uniform - asrdirmga
Grizzlies, Hawks, Mavericks, and Rockets secondary road uniforms - eydonscar
Bulls, Celtics, Knicks, and Raptors St. Patrick's Day uniforms - riiasgerh
Trail Blazers Rip City uniform - ycprtii
MJ: Creating A Legend - icanbe23

At the start of a season you get 10 new drills.  Before beginning your new drill, subtract on point from you 3 point stat, which gives you around a 1000 skill points to spend on anything else. Then, complete a shooting drill by attempting only 3s to get your 3 point attribute maxed out again. This is an easy way to get extra skill points. You can do this anytime you get a drill.

At the Main Menu, scroll down and select "Features", then "Extras, then "Codes". At the codes screen, unlock the following dunks by entering the correspinding codes. Note: After entering the code, load up the Sprite Slam Dunk Showdown and check the Dunk Help menu to view how to perform the new dunks:

DUNK - CHEAT CODE
"Orange Split" dunk - SPRITEDUNK1.
"Spin Tommy" dunk - SPRITEDUNK2.
"The Villain" dunk - SPRITEDUNK3.