That depends entirely on whether you mean the religion of Wicca, or the word Wicca as used pre-gardner which is just the Old English form of the word witch and was a regional word for cunning person before witchcraft became its own thing splitting off from the cunningfolk.
To practice the religion of Wicca you have to be Duotheistic, recognizing a God and Goddess. You do not necessarily have to be theistic in the sense of literally believing in them as entities exterior to the self but you do have to work and form relationships with them.
If you are wanting to practice traditional Wicca, and are seeking to be initiated into a Coven, that Coven will tell you the names of the Lord and Lady of the Wicca. These are the names and entities you will work with as the God and the Goddess while working within that tradition. In your personal, non covened practices you may use the implements and techniques you have learned to work with your own specific matron and patron deity - though a traditionalist would argue that you arent at that point practicing the mysteries of the Wica per say so much as you are using your Wiccan training and format to explore other mysteries. Some would way it is still Wicca because your matron and patron are aspects of the God and Goddess. Though there will come a time when your personal practice is no longer the practice of the Wica but has become its own thing- which is a good thing. That's the natural progression of the path. It is fine just so long as you arent claiming it to be something it isnt.
You can use a Wiccan circle framework to work with any deity or spirit, but I want to be very clear. Working with a Hellenic goddess in a Wiccan circle format does not make you a practitioner of Hellenic magic. IT makes you someone who is using the magic that was taught to use as a Wiccan to make contact with a Hellenic entity.
On that note if your path is very devotional and centered on a specific entity such as a deity, then you might forgo the Wiccan structure altogether and practice something a lot closer to what that deity is familiar with. There is power in affiliation and tradition.
Of the implements in Wicca, Wicca as in the Wicca derived from the work of Gardner, draws on both Solomonic methods as well as Golden Dawn methods in its ceremonial praxis.
While your personal matron and patron can be from any pantheon , if you have to ask you really should not be mixing pantheons. Especially if the deities in question come from peoples who did not get along. You may very well have to keep the peace if you attempt it. It probably is not worth your time unless you are of mixed heritage and you are trying to reconcile conflicting forces within you, then it is of utmost importance.
Dont go mixing different systems until you have practices each of the systems on their own terms and have a degree of competency between them. Also try not to mix invocations and active words in differing languages. Languages are systems within themselves and have an inherent syntax, muddling them muddles the psyche as you are attempting the work.