How many leganderies can you get in Pokemon Pearl?
You an get 14 legendaries: Rotom, Uxie, Mespirit, Azelf, Palkia, Heatran, Regigas, Giratina, Cresselia, Manaphy (through Pokemon Ranger), Phione (through breeding with Manaphy and Ditto), Darkrai (through Mystery Gift), Shaymin (through Live Events), and Arceus (through Live Events). From: Austin the Pokemon Master
There aren't many, but I would recommend Pearl for it's tough Pokemon legend, Palkia! But the main differences are... Different Pokemon appear at different times and places. The legendary Pokemon at Spear Pillar is different. (Palkia for Pearl, Dialga for Diamond) Hope this helps you! The Pokemon Master