ROUND 1: 1st or 2nd stage evolutions with weak STAB moves (e.g. Confusion) and a variety of other moves. AI is completely random.
ROUND 2: 2nd stage evolutions or weak fully evolved Pokemon (e.g. Arbok) with semi-weak STAB moves (e.g. Psybeam). AI is completely random.
ROUND 3: 2nd stage evolutions or weak fully evolved Pokemon with a strong STAB move (e.g. Psychic) and 1-3 other strong attacking moves. AI won't use useless moves (e.g. Thunder Wave when paralyzed, EQ on Flying types). A few Smart AI clauses are present (e.g., don't Will-O-Wisp Pokemon that resist Fire). AI's attacking moves are random.
ROUND 4: Strong fully evolved Pokemon with a strong STAB move and EVs in Attack/Sp. Atk/Speed. Other moves are typically weak (e.g. Facade) or non-attacking. AI won't use useless moves (e.g. Thunder Wave when paralyzed, EQ on Flying types). A few Smart AI clauses are present (e.g., don't Will-O-Wisp Pokemon that resist Fire). AI's attacking moves are random.
ROUND 5: Strong fully evolved Pokemon with a strong STAB move and EVs in HP/Defense/Sp. Def and a variety of other moves. AI is smart.
ROUND 6: Strong fully evolved Pokemon with a strong STAB move and 1-3 other strong attacking moves and EVs in Attack/Sp. Atk/Speed. AI is smart.