1. Bag items are disallowed, such as the use potions of any kind to heal or cure Pokemon
2. Leaders and challengers must use at least 6 Pokemon
3. You may only challenge the same Gym Leader once per day(unless they say otherwise)
4. Gym Leaders must use their own Pokemon
5. Both trainers must use Pokemon that are level 100 or less
6. There is Species Clause for both Challenger and Gym Leader. If you don't know what Species Clause is, you can find it here
7. There is Evasion Clause (No moves that boost the evasion stat like Double Team and Minimize)
8. Do not exploit broken moves, abilities, or pokemon, or you will be disqualified. If a leader breaks this rule, they accept an instant loss and the challenger shall be given that badge. Any leaders found to be repeatedly break this rule after having been warned will be stripped of their position.
9. Pokemon that can change types during battle (Kecleon, Castform, MEGAS, etc.) can ONLY be used in the gyms of their original type. For example, Protean Greninja in Dark/Water, Castform in Normal, Mega Aggron in Steel/Rock, Mega Lopunny in Normal.
10. Ubers pokemon (including mega evolutions banned to Ubers) are banned for use in /info gyms unless explicitly listed otherwise [PAY ATTENTION TO THIS:]
11. Gym-Type specific banned pokemon are not allowed to be used by challengers against gyms of their respective type (for example, if blaziken is banned against bug gym, challengers bringing a blaziken to challenge the bug gym will be disqualified)

Note: Remember to check if your next challenger is ready for you to accept their challenge, may it be through MSG or In-game chat. If there is no response, cancel their challenge and move on.