Is asking for advice between game sessions cheating?

[Killer Angel]

He's complaining about things other groups are doing...?

Well, judgin from the OP, there's nothing that points to Jones' group.
Of course, I can be wrong.

Which I why I say (in a now-general, non-specific sense); if a DM's players are going to the forums (regularly) for help specifically in dealing with his encounters (i.e. as opposed to more general advise) as postulated by the OP (and the DM has a problem with that), maybe the DM ought to have a close look at why they are doing so, because it's likely to be something that's symptomatic of an underlying issue.

Well, if this is done regularly, certainly there's a problem. If the problem lies in the DM, the player(s) or both, who can tell?

Really? Planning tactics in advance? I usually only plan an encounter's setup. Tactics is a fluid thing, you have to adjust as you go. Even the best plan fails, as soon as the first shot is fired.

Not always.
Scry 'n die requires the planning of an attack.
Sometime, in a certain situations (guards in a castle, etc), you can have a pre-determined tactic for certain situations, that the guards will follow.
You plan tactics in advance. Only, more often than not, they don't survive the battlefield.