Wrathamon said:
My buddy is running a 3.5 game (coming from 3.0) and is using all the core + complete books. He is worried about any inbalances in the game that may or may not come up.
Honestly don't even try to find them. That's your best bet. 3.5 is full of holes, significantly more if you tabulated all of them than 3rd edition I'm willing to wager.
My suggestion is just to play and have fun, if something shows up, the DM should do his job and knock it back down to size.
You can do all sorts of stupid things with the rules. Take 3.5 wish for instance. In 3.5 you can wish for an item that costs more GP than 15 000, all it costs is more XP. But Spell-like abilities (Sp) specifically elliminate that cost. So if you can get access to a creature that grants Wish (planar binding, etc...) you can have it create a ring of infinite wishes with one wish. Same applies to the plain old ring of three wishes, just wish for more rings of three wishes. Infinite wishes.
3.5 Shapechange is very very poorly thought out. PCs should never have access to Supernatural (Su) abilities of creatures. The errata HD cap does little for game balance. If you want you can shapechange into a balor which gives you a vorpal sword 1 per round. Creating in essence piles of vorpal weapons. You can turn into Barghest and devour ennemies for infinite HD gain. You, your familiar and your animal companion(s) can shapechange into a different dragon type each round and breath for ridiculous damage (it's a personal range spell and so can be shared). Or you could have your familiars and animal companions turned into balors to project huge anti-magic fields around you.
The point is to use what works for you and can the rest. If you have a 3rd edition PHB I suggest switching those two spell immediately, and holy word/blasphemy too. But you could also play within reason using the rules.
Non-core there are too many options and power combos to list. The complete series are
not balanced, at all. Just work with the DM if and when the issues arise.