Are mostly Pokemon in anime voice is based on their name? Take example like Pikachu said Pika Pika! or Pikaachuu! and Chansey said Chansey! I don't watch the anime, so I don't know much about Pokemon anime voice.
Yup completely correct
In the anime a Pokemon's 'speech' is generically just a repetition of their name and/or parts of their name. Or the other way around (They're named after how they talk! :D)
There are of course some exceptions to this rule, including Pokemon like Onix saying their Japanese name, Pokemon like Starmie/Staryu making cries which don't relate at all to their name
and Meowth talking human but otherwise it's like that
[Here] is the Bulbapedia site relating to it.
Otherwise watching heaps of the anime =)