My friend and I play Remix almost everyday for an hour or two and we always have a blast. We play regularly with 20k starting against each other.
I can send some early units at him but already he has an unbreakable wall of 3-4 defenses and infantry squads and my units are quickly dismissed. All my future attacks are subsequently slowed by artillery hidden behind his defense line or by his extremely powerful planes. Late game, he builds a nuke silo behind his wall and no plane, tank, or infantry can pass to stop the launch. This is especially hard with Tank general, whom I play regularly. His tanks are too bulky and expensive to keep attacking the front line and my ranking is too low to build super weapons myself.
This leads to my final element, what are some tips for Tank vs Nuke general? I wish to finally beat him and show him that he cannot just turtle. If you need a replay, I can provide one.
If he's turtling your best weapon early game is the sniper cannon, it's long range should out hit all his early units and defenses. I expect he's probably using nuke cannons as his mid game defense, these have great range, but are very frail. It may be a suicide run for many of your planes, but you can pop them with Migs moments before a ground attack made of mostly sniper cannons. This way you can destroy his defenses safely at the cost of a few aircraft.
Build plenty of ECM tanks and manticors for his aircraft, and make sure every unit you send is near a command tank.
btw, in this case I would recommend your first point be spent on ecm tech. The most important think is missile defense, but once you can get the upgrades you can shut down his defenses and aircraft too.
By the mid/late game heavy Artillery guns (mini super weapon) are your best bet for destroying his nuke cannons and this should let your snipers and earth shakers get close enough to fire on the defenses.
Once you hit Rank3 you're options open up a lot vs a turtle player. You can get the next rank of ECM for the upgrades. This will also allow you to ECM his aircraft. I don't normally recommend an artillery barrage, but just 1 point can be great for destroying his nuke cannons. If you use lightning the Tien Mu can be given "attack ground" orders just in front of his defenses to start hopping chain lightning in from a safe distance.
ECM artillery can be a kick in the ballz for a turtle player too.