If you dont get hit in the timeout then we agree that you have successfully "evaded" That is why we have the timeout on most of these commands.
Command that are instant are the commands that are frowned upon. Such as /afk. <--- (Will get you severely punished)
Enderpearling away and then typing /home is a fair method of trying to escape.
As for fly, If you start flying during pvp, that is breaking the rules. We understand accidents happen, and everything will be taken on a case by case basis. But once you have been struck, if you were not already flying (And I mean off the ground), you cannot fly during pvp.
If you are attacked while flying (boots visibly off the ground) = Okay to use fly during PVP. (Even if they are not, since by our logic they knew what they were getting into)
If you are attacked while not flying = Not okay to use flying during PVP
If you see someone flying and you also have fly = Okay to engage in mutually flying PVP (since you both have fly, even playing field)
If you see someone flying and you do not have fly = Okay to engage in PVP (But be warned, if they are attacked while flying, they can continue to use fly for the duration.)
I feel like most people knew the majority of these, but here it is spelled out as best I can.