There was only so much they could do on the GBA, and they had already created a great game. He was definitely struggling with his darkness It is shown in his portrait. red eyes and messy hair, and overall "scary" appearance, where even Mina was frightened of him. Theres really no effective way to portray that in game, but the "bad end" you get from loosing to Chaos tells the tale good enough. He was already fighting it off, and when he looses, he looses tot he chaos within himself.
Graham? what more is there needed. its explained "all there in the manual". He's a cult leader who wants to inherit Dracula's powers. he doesnt need much more expose than that. He wasnt born upon Dracula's defeat, so he has no special powers of his own. The 1999 battle has little information itself other than "Julius was in it", "Dracula revived according to prophecy", "great war was held, Dracula was killed for good and his castle sealed away"
thats just about it. its a past event that needs really no more explanation than that.