About entry hazards - for an offensive team, how much they're worth depends on how many of the AIs team members gain nHKOes on how much of 'the metagame' with the hazard. This can be done by running damage calcs with the team members as offense, against the Smogon standard sets on defense, weighting for usage, and perhaps considering the 'need' of the nHKOes. (A team with 2 good Mence checks, only one of which needs SR, needs the hazard less than a team with only one decent Mence check that requires SR).
For stall teams, it's rather different. There, I might guesstimate how long the hazards will be up for (which depends on how likely the opponent is deemed to have Rapid Spin and whether the AI has a spin blocker), and therefore calculate the percentage damage they should do (based on any information about susceptibility to hazards of the opponent's Pokemon), then compare that to the expected damage from the AI's other move choices.
I may be being naive or missing something, but I think you'd get a good algorithm just by running probabilistic damage and nHKO calculations. Almost everything useful a Pokemon can do relates to damage. Attacks, poison and burn, entry hazards, and phazing with entry hazards cause it. Stat boosting increases the ability to cause it. Healing moves remove it from yourself. All status except poison (including Taunt) inhibits the opponent from causing it to you or healing it from them.
You could insert a large 'gap' between 1 and 0 HP, to encourage KOing a weak Pokemon rather than denting a strong one. You might also add a small weighting towards reducing uncertainty, so the AI would 'scout' if it's running a phazing move.
"If I may guess, Emboar might be an exception to the norm that the scalding liquid is expelled from the Pokémon's mouth" - Cobraroll, on Emboar learning Scald.
"Nothing like a cup of tea to start off the day" - Professor Oak, EP025.