To do the invisible cheat you must first join a game. While inside the game, go to the console (~ key) and type: model freeza. Then Type this: model dracula. This will make you completely invisible unless you be batman. If you are batman and do the invisible cheat then your back will have letters that say: "I am a cheater".
Spam Special Weapon Cheat:
First, start a game and go and get killed. DO NOT RESPAWN. While dead go to character select menu and pick Megaman. *While Dead* Press the 1 key on your keyboard. This will activate Sub-T. Then pick whatever character you want DONT RESPAWN!. Then with that character while your dead, press the 4 key on your screen, this will activate the character you picked's special attack.