Hi can you be any pokemon to recruite Pokemon into your team. For example..

That depends, if you were Moltres and trying to recruit Groudon it would be impossible, because you party can only have up to a size of 6 stars. Their size are both 4.

Yes, but you have to following certain rules
1) Team Member: the number of team members must be less than 4 (if you play DS, on the upper screen you will see there are 4 slots for 4 pokemon), if you have already had 4 then no more can be recruited.
2) Team Size: If you want to recruit a certain Pokemon, you have to add up your current team size AND the Pokemon you want to recruit, the number must be less or equal 6. You can't use Moltres to recruit Groundon because Moltres's size is 4 plus Groundon's size is 4 and we have the sum of 8 bigger than 6. Size can be found at the 3rd page of summary of each Pokemon. Almost all legendaries have the size of 4, except Mewtwo, Mew, 3 regi, Deoxys, Celebi, Jirachi, 3 legendary dogs which has size of one and Latios, Latias has the size of 2.
3) You can be any Pokemon, but you must reach a level to recruit certain Pokemon with/without Friend Bow.
4) The leader must be the one who make the final blow.
5) Luck

No you can't be any Pokemon because there is a size limit so you can only have 6 stars max.moltres the other birds groudon and all those big legendaries have 4 stars so you can't recruite a legendary with another legendary but you can recruite any other Pokemon with a legendary just not a legendary pokemon