So, there are a LOT of bugs with Pet Battles at the moment. Some are extremely common (Duplicate pets, accuracy issues, Wind-Up bugging out passives, Dragonkin passive quirkyness, etc) and some are extremely obscure ("loss of control" bug, battle crash with Terrible Turnip/Lil' Ragnaros, Snap/Magma Trap bug), but almost everything on this list is important (well, the tooltips are less important but also much, much easier to fix).
It would be great if people could help get the word out about this thread (i.e. request sticky, mention to your friends, etc), but most importantly, if you know of a bug that isn't on this list, please post it and detail as much information as possible!
To see what's been fixed so far in Patch 5.2, go here! - http://us.battle.net/wow/en/forum/topic/7708412656 and http://us.battle.net/wow/en/blog/8226552#pet_battles
General System-wide Pet Battle Bugs (in order of severity)
- Spell Stacks: Spells that increase in damage each time they are used (Arcane Blast, Frog Kiss, Sleeping Gas, etc) reset every time the enemy pet is swapped or dies. This makes them less effective than normal attacks because it is rare that the opponent will leave their pet in Battle for more than 3-4 rounds.
- Accuracy Issue #1: All Heals and Buffs can miss when accuracy debuffs are in play (such as Call Darkness, Sandstorm, and Stench). Additionally, several Heals and Buffs can miss AND can be dodged without any debuffs active. That bug has been confirmed to occur with the following abilities when no accuracy modifiers are in play: Decoy, Uncanny Luck, and Wish. I believe that many Weather abilities have the accuracy of their secondary effect (applying the weather) set to 200% to avoid this bug. It is likely you could solve this issue by changing the accuracy % on heals and buffs to 200%.
- Accuracy Issue #2: Additionally, +/-accuracy effects (Call Darkness, Stench, Uncanny Luck, etc) AND the base dodge/miss chance are incorrectly applying to secondary ability effects. For example, it says that Screeching Gears has a 25% chance to stun. In reality, this is more like 15% (after dodge/miss) and if there is a Sandstorm/Darkness present, it is actually 5%. Basically, it causes double-dipping RNG with any ability that uses two rolls.
- Accuracy Issue #3: This DOES include things like Slicing Wind (hits the enemy 1-3 times for X) and Thrash (hits the enemy for 1-2 times for X or 2-3 for X if it goes first) because it takes +/-Accuracy% and base dodge/miss into account when calculating how many times to even attempt to hit, then does the roll for dodge/miss on top of that. For example, with Stench active, Slicing Wind will -never- attempt to hit 3 times. It will always only try for 1-2 hits.
- Damage Reduction: The order of operations in the Damage Reduction formula is very likely incorrect. Currently, it is (Damage from attack – damage reduction) * damage multiplier. This strongly weakens the viability of moves like Swarm and Flock, which rely almost entirely on that damage multiplier to do damage. Damage reduction should be subtracted from the overall damage after all other factors are considered.
- There is a floating point error in your Rarity variable, causing most pets to have incorrect stats when they are Rare and above level 5-10.
- There is a floating point error in your Wild Pet HP nerf's variable, causing most wild pets to have even more incorrect HP values.