The railroad graveyard is the ideal place. The most ideal place for training, with a wide array of monsters to battle against. A great way to increase their strength and increasing their magic abilities.
The graveyard is underneath the plate, so while training they are protected from the eye of Shinra. As Shinra never pays any attention to what goes on under the plate.
The varying levels of monster, allows Cloud to get a handle on a number of different swords. In the event of him loosing his main weapon during battle, Cloud will still be able to fight with a substitute weapon.
The decaying train carriages, also provides great training on uneven ground. With the outlying land surrounding Midgar, is either flat and smooth or rough and uneven. Being able to fight on different types of ground surfaces, provides Cloud and the team a greater advantage.
The abandoned train carriages, also hold unexpected treasures. It takes just one moment between fights, for Cloud to explore them and the surrounding areas to find these treasures.
While waiting for AVALANCHE to make their next move against Shinra. The graveyard offers the best ground for training. With this training Cloud and the rest of the team will be ready to bring Shinra down for good.
A little dip into the world of Final Fantasy VII. Let me know what you think.