Is there any way to get the required military strength for the best ending without online and without DLC?
Without DLC the EMS requirements are 4000.... which means.... NO, not possible, as you can only collect somewhat 7500 EMS points at best. Multiplied with the standard fReadiness Rating .50 for single player only leaves you with roughly 3750.
The free DLC Extended Cut loweres these requirements down from 4000 to 3100..... giving you a good a fair amount of room to maneuver and play around in what you want to do (saving Council yes/no, cure Genophage yes/no, Geth or Quarians just to name a few). Remember, as long as Anderson survives the TIM encounter (Andersons survival is worth 1000 EMS!) you have 1.800 EMS at your "screw them" disposal.
Short answer..... to get the "perfect" ending, DLC Extended Cut is a must have, if you want to avoid Multiplayer gaming.
masseffect.wikia.com/wiki/Priority:_Earth (section 'Aftermath')
A method that has worked for me is to play the multiplayer until 100% Galactic Readiness, then signing out of online play. In offline, Galactus Readiness stays at the last percentage from online and never decreases. It worked on PS3, but I'm not sure about other systems.
It does work on PC aswell. You go online, play some Multiplayer matches to raise your Readiness. If you sign out, your Rating won't decline, for as long as you do not go online again. But as stated before, it won't be possible without the Extended Cut DLC or some Multiplayer matches.
Mass Effect: Infiltrator and Nass Effect datapad( I can't find infiltrator on iOS nor datapad but I found that on IGN)
Both were taken down
What do you think?