Fight Song
Q. Is Altaria's "Fight Song" Ability stackable so attacks from Dragon type Pokemon can do an additional +20 damage for each Altaria in play?
A. Yes, it does. (Aug 23, 2012 TPCi Rules Team)
Thank you so much for answering!! :- )It doesn't say that only one ability can be active at a time, so yes, you would get +60 from three Altaria.
Thank you for the answer!!You can find more rulings at http://compendium.pokegym.net/compendium-bw.html. The website isn't owned by Nintendo/TPCi but the people who do own and run it include members of the official Rules Team for TPCi. As the name implies, it is a compendium or compilation of official rulings.