"Mokey Mokey" itself is a Normal Monster, but by involving "King of the Skull Servants" and "Mokey Mokey Adrift", it suddenly transforms into an aggressive card
The sentiment that Konami uses the banlist as a form of soft rotation, alongside general power trends, is soundly held by many in the community
Standard also has two other creatures with this exact mana cost: Craterhoof Behemoth and Ghalta, Stampede Tyrant, which are much more proactive threats
As far as which has the highest equip cost, Belt of Giant Strength is technically the one with the highest, but it varies depending on the creature it targets
Note that this means it is more difficult to get the deck recipe from and trade with duelists who max out at :) grade
Surface issues are the second most common PSA 10 rejection cause for OPTCG