hunt the hunter

[particle]

{hunt the hunter}
must both creatures be green for any and all parts of this spell to resolve?

[Mattao19]

{hunt the hunter}
must both creatures be green for any and all parts of this spell to resolve?

Yes both need to be Green

[Pleeb]

114.1.: Some spells and abilities require their controller to choose one or more targets for them. The targets are object(s), player(s), and/or zone(s) the spell or ability will affect. These targets are declared as part of the process of putting the spell or ability on the stack. The targets can't be changed except by another spell or ability that explicitly says it can do so.

In order to be put on the stack, all targets have to be declared. The spell targets two green creatures. If your opponent doesn't have a green creature, you can't cast the spell.