
The official Pokémon TCG Alternative Play Rulebook relies on randomness for most of the choices the Raid Boss Pokémon needs to make, including choosing its attack. In essence, this makes the Raid Boss Pokémon less of an antagonist, and truly more of a wild Pokémon. The added benefit of this is reducing the number of players, as someone could take on the role of performing the Raid Boss’ actions, while playing their standard deck.
The inverse is true — someone could choose to actively play as the Raid Boss Pokémon, making choices when resolving card effects, and choosing the attack. These options are detailed below. Easy and Medium difficulties allow for someone to play as both the Raid Boss Pokémon and as a player. Hard and Extremely Hard require a dedicated person for that role.

Easy
The easy difficulty uses the standard rule set, but any choices (except for attacking) are made by the Players. In addition, card texts would be interpreted as literally and generously as possible. For example, consider Boss’ Orders. Its effect reads:
Switch 1 of your opponent’s Benched Pokémon with their Active Pokémon.
The most generous reading of this would be one of your opponents must switch one of their Benched Pokémon, and as a group, they could select both the Player who will switch a new Pokémon to the Active Spot, and their new Active Pokémon.
Another example would be Miss Fortune Sisters:
Look at the top 5 cards of your opponent’s deck and discard any number of Item cards you find there.
In this case, the Players would make the choices. As a group, you could decide for each card requiring a choice that at minimum one card would need to be selected.
Otherwise, all actions remain random, including Attack selection.

Medium
The Medium difficulty plays much the same as the Easy difficulty, with a slight modification: all decisions are, as much as possible, random. For example, if Boss’ Orders is played, the player who would switch a new Pokémon to the Active Spot would be chosen randomly, and the new Active Pokémon would also be chosen randomly. (See “Randomization“.)
Likewise, for Miss Fortune Sisters, a coin could be flipped for each Item revealed to decide if the card should be kept.
The Medium difficulty retains the spirit of the Raid Format as laid out in the official Pokémon TCG Alternative Play Rulebook, in terms of randomness.

Hard
Hard difficulty shifts things up a bit — the Raid Boss Pokémon will make decisions for Trainer cards and Pokémon Abilities. Cards are interpreted favouring the Raid Boss Pokémon. For example, Boss’s Orders would let the Raid Boss Pokémon choose a new Active Pokémon. As a group, the decision could be made whether this would affect one Player, or all Players. At this difficulty stage, a separate person must make decisions for the Raid Boss Pokémon.
Attacks are still chosen at random.

Extremely Hard
Extremely Hard shifts the difficulty up even more. Everything from the Hard difficulty is still valid. Decisions are made by the person playing the role of the Raid Boss Pokémon, including attacks. All opportunities where there might be randomness are now directed by the Raid Boss Pokémon player. Cards should be interpreted through the strictest possible sense to benefit the Raid Boss Pokémon.
Another option to increase the difficulty is to adjust how damage is converted to cards sent to the Lost Zone. For three players, instead of dividing by 30, you could divide by 20 instead. In the damage calculator, you can enter a falsely lower number of players.