@Zale: Um...Wish's question troubles me. Yeah, better add these to the rules.
CANNOT have all the same Pokémon (at least not until WAY later in the game; and if/when you do, you must catch them, therefore requiring the same bond formation as with any other)
And YES, you have all the same weaknesses of the Pokémon you currently mimic.
Legend:
+: its super effective
-: Doesn't do well against it
=: no effect
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)