Golduck can move any color basic energy from one Pokemon to another, so he can be the centerpiece of a toolbox deck that uses many different types of attackers so you can choose the one thats most effective against your opponents deck and, ideally, hit for weakness
A 3-mana 2/2 is generally bad, even if it dies into an equipment that gives +2/+2 for
The Gameplan A few examples: Turn one Legions Landing, turn two Saproling Migration, turn three Song of Freyalise plus History of Benalia does 16 damage
Path of Ancestry ($2) I like Red XIII being on the cliff here, but I also love a special version of a card in 130,000 decks on EDHREC getting a special version so cheap
Obviously this gets a lot better with more Xathrid Necromancers
Grixis Charm is an interesting one