Let's see what he's talking about here:
The Symbiotic Creature template, in Savage Species, which combines a 'host' with a 'guest' to create an end result. That end result has a +1 LA, uses the HD and physical stats of the Host, and the mental stats of the Guest. You retain all of the special attacks and special qualities of both creatures. The Host must be at least two sizes larger than the Guest, and both must be from the animal, humanoid, plant, or vermin creature types. Also note that the end result's creature type changes to Aberration, so he would not retain any benefits of the plant creature type (immunities, etc.).
Just to point out, that's
one of the more abusable templates in the game due to the fact that it ignores the HD and LA of the Guest. At least he's not trying to throw
Paragon onto the Guest.
Awaken can be cast on
an animal or a tree, nothing else. An Empowered + Maximized Awaken will give an awakened
tree Int, Wis, and Cha scores each of 18+(3d6/2), which will average 28.5. Note that an awakened
tree is friendly toward the individual who cast Awaken, and with the plant creature type they're immune to anything mind-affecting, which could include Diplomacy at the DM's discretion.
Note that a friendly attitude is not enough for it to permanently bond to another creature unless it's in the best interest of the awakened tree, assuming the potential Host is even the one who cast it. Also keep in mind that trees are extremely long-lived and grow quite large, so it would probably prefer to attach to a creature which will live quite a long time and give it the greatest room to grow, so the bigger the potential Host the better. Remember that a Host can only accommodate a Guest of two sizes smaller. It may outright abandon the PC for the first giant that crosses their path, as that would give it hundreds of years and plenty of room to grow.
So there you have it, almost zero chance of convincing an awakened tree to become a Guest unless you cast Awaken yourself or you happen to be quite large and are expected to live hundreds of years. Think of the Ents from the Lord of the Rings and their attitude toward adventure, that's how an Awakened Tree would feel so it would be far more likely to attach to a lazy ogre. Even if a PC gets one as a Guest, it could abandon him without any notice if a bigger, less adventurous potential Host were to reveal himself. So by DM discretion, it actually balances itself.