Do any leagues in Yahoo fantasy baseball have a problem with teams picking up numerous free agent pitchers?

If I understand your question properly, there is someone that keeps switching pitchers daily based on who is pitching the following night. Unfortunately this happens sometimes in H2H leagues because there are unlimited moves. However, this doesn't usually happen until near the end of the season.

Note that they usually kill their ERA and Whip when they do this and win the Wins and K cats. Frankly, I think it ruins the spirit of fantasy baseball and that there should be a limit placed on moves, but right now that only occurs in custom leagues. I hope this is what you meant.

BTW, if they drop any top tier pitchers, pick them off the waiver wire and leave them the "junkers."

Not unless there is a move limit. And to be honest, anyone that carries more than a couple of bench hitters after June 1st isn't gonna win their league anyway. Stock up on pitchers early, discard guys that get shelled once the weather gets warm, and replace them with hot hands. And keep in mind, even with roster move limits, most moves are made early on anyway - it doesn't do you any good to finish the year with the most available moves left and unused. But keep some in reserve to make sure you can attack whatever categories you need help with on or about August 15.

how do u pick up a free agent pitcher in yahoo fantasy baseball league I don't know I need help

Some leagues hav a maximum roster moves.

You can have as many pitchers as you want. If you have too many pitchers, you wont have enough fielders.