Which of Greninja's types changes after it uses an attack (with protean ability)?

Question

For instance, if Greninja used Earthquake, would its type be Water/Ground, Ground/Dark, or Ground?

Answer 1

Greninja's type would be Ground. Both of Greninja's types would be replaced by the type of the move it last used. The same goes for any other Protean Pokemon; if it happens to be a dual type, it would make no difference, and it would not keep one of its regular types,

Source: Many experiences with Protean Greninja in online play

Comments

Thanks; I'm really glad this question got answered.

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No problem, glad I could help! :)