(Ok, now it's Gohan's turn)
65: Pump points into Strength, but don't bother with Wool Mittens. They're not worth the time to put on.
(After breaking Goku's gate and switching to Gohan, go Super Saiyan)
66-70: Nothing
71: Pump all points into Strength (allows Majin Soldiers and Fighters to be killed easier)
(After you get past the Destroyer bot, you'll find a small area with two Majin Fighters and Two Majin Soldiers. Grind here, and make sure you get some Demon Mask's here, for they are accesories that give their wearers 7 Strength. With the Brass Knuckle that's buyable at the World Martial Arts Tournament, that equals 16 extra Strength total, which is handy once you reach the point where you can't pump Strength past your level. Also, I would suggest farming some Fancy Tuxedo's here to, as they sell for 2500 Zenny apiece, which is great as at a future Z-Mart, there's some gloves and armor that radically boost your power. Buying the two of those costs 10,000 Zenny total).
72-75: Nothing
76: Pump everything you can into Strength (This makes every enemy here killable in one hit. You could do that at Level 71 as a Super Saiyan, but 76 is about as far as you can go before Gohan reverts back into regular form).
77-84: Nothing
85: Pump everything you can into Strength, and equip a Demon Mask and Brass Knuckle.
(Switch to Vegeta here. He needs to really boost his Strength so that he can kill Fat Buu quickly, as he is only vulnerable after you hit Babidi, so you'll want to beat Buu in one cycle).
76: Equip Leather Glove and Demon Mask
77: Pump Strength (Majin Fighters are killed in one shot w/SSJ)
78: Pump Strength (Majin Soldiers are killed in one shot w/SSJ)
79: Nothing
80: Pump Strength (Both Majin's are one-shotted in regular form)
81-85: Nothing
(Switch to Goku here to fight Vegeta)
71: Pump Strength (Self-Explanatory)
73: Pump Strength and equip Leather Glove (Self-Explanatory)
74-76: Pump Strength (Self-Explanatory)
(Switch to Vegeta, on his quest for Fat Buu's head)
86-88: Nothing
89: Pump Strength and equip Brass Knuckle (You need to end the Fat Buu battle as soon as possible).
(Switch to Goten now, as we start the most annoying segment in the game. Now, the only place either Goten or Trunk's can go to is the Warlord's Ship, so the route I've devised involves sending Goten through the Warlord's Ship first to get him a ton of levels so that he can break that Character Gate later that requires him to be level 100. Then, have Goten go through the Diablo Desert until he gets to the save point. You'll then want to switch to Trunks and have him kill all of the enemies on the train. That will only be enough to get Trunks to Level 79, so you'll have to stop for a short bit to gain that extra level. After that, the route is unknown to me).