Each deck was capable of being the archenemy or being on the hero team
The central gambit here is using Squee, the Immortal as an always-available infinite combo piece, though most of the infinite combos are fairly convoluted (3-4 cards)
The key tweak is the shift in how energy works: rather than filling your deck with specific energy cards, you simply select the type (or types) of a deck when building it, and energy is automatically generated once per turn for you to attach how you wish (for two-type decks, which are required for the Dragon Pokmon lines such as Dragonites, which type comes up next is randomised, which effectively replicates a multi-type deck equivalent in real life)
After all, unlike in 60-card formats where you are trying to deal 20 damage to just one opponent, in Commander, you have to deal with three opposing players, all starting at 40 life and all acting in their best interests