he said his father trained or worked with him at an early age to do this. I had friends that tried to train their kids to hit righty and lefty but it didnt work. It’s really amazing.

But it was my understanding that a pitcher was required to be introduced and at that time his “arm” declared… similarly to how a batter must “declare” whether he’ll be batting from the left or right batters box prior to an at-bat. I had a debate with a friend about the value of an ambidextrous pitcher a few years back and after some research we found this obscure rule… perhaps it’s been changed since, but at the time it seemed useless to have a pitcher who could throw left and right pitch the same inning as the pitcher was required to declare which he’d be throwing for his outing… could be wrong.

Here he is facing a switch-hitter: http://www.youtube.com/watch?v=-2oD8KzxS14

The fun starts at about the :45 mark.

As for rules for ambidextrous pitchers, MLB.com has this to say:

I have a question regarding pitching. Is there any rule that stipulates that a pitches must either right-handed or left-handed?

No, there is no such rule.

Based on the answer to the first question: If not, it is feasible to say that a pitcher could deliver the ball right-handed one pitch and then left-handed on the next?

Ambidextrous pitchers are rare but do exist. An example was Greg Harris, who pitched with the Boston Red Sox. When such pitchers pitch in the Major Leagues, they must pitch with the same hand during a batter’s entire at-bat. Such pitchers may change pitching hand for the next batter, but again must continue with that arm for that batter’s entire at-bat.

If there are glove stipulations, could a manufactured glove that fit either hand be worn?
— Nicholas K. Kruse

This would be legal under the rules, provided such a glove meets the specifications outlined in Official Baseball Rules 1.14 and 1.15.

(Source [mlb.com]:Ask the Umpire – By Tom Leppard – Director, Umpire Administration)

Note: The page source indicates that this was written in or before 2007. I can see no reason why the rule would have been changed just because there was a new ambidextrous pitcher attached to a club. I do, however, remember discussions of a rule change because of the Venditte-Henrequez AB above.

Aha:

In order to avoid such incidents in the future, the Professional Baseball Umpire Corporation (PBUC) released its official rules for dealing with ambidextrous pitchers on Wednesday. These guidelines were reached after PBUC staff consulted with a variety of sources, including the Major League Baseball Rules Committee.

At the heart of the new guidelines is the following provision:

The pitcher must visually indicate to the umpire, batter and runner(s) which way he will begin pitching to the batter. Engaging the rubber with the glove on a particular hand is considered a definitive commitment to which arm he will throw with. The batter will then choose which side of the plate he will bat from.

“The basis for the rule is that everything the batter does, he does so knowing what hand the pitcher is going to throw with,” explained PBUC executive director Justin Klemm. “He may not know what type of pitch is going to be thrown, or its location, but he does know which arm will be used. A manager selects a pinch-hitter based on that knowledge, and that is also how a switch-hitter determines which side of the plate he is going to bat from.”

The guidelines also permit both the batter and pitcher to change positions (from right-handed to left-handed or vice versa) once per at-bat.

(Source [minorleaguebaseball.com])

So it would appear that in the minors, one is allowed to switch pitching arms once per PA after indicating the arm with which one will start the PA. However, in the majors, once one chooses the arm with which they will pitch the batter, they must stick with it throughout the PA.

I saw him for Creighton against the University of Memphis. I thought he was better lefty than righty. He’s got nasty junk left-handed but throws harder righty.