I'm not saying they would beat him, I'm saying they could do damage. It looks like people are saying f the 8th gate when they haven't even seen it yet or 7th gate with Kyuubi chakra. I wonder if Naruto open all 8 gates would they say the same thing.
Gai- His Taijutsu is already effective on Obito but now has Kyuubi chakra stronger than ever. The kyuubi with just yin(or yang idk) was able to heal him 100% from the 7th gate so now with yin and ying together will make him even more durable....durable enough to survive the 8th gate! Make it happen Kishimoto, all 8 gates Gai with Kyuubi chakra= a match for Obito.
Lee- pretty much what I said about Gai except with 7 gates maybe instead of all 8. We haven't seen everything 7 gates has to offer like running speed and combos cause all Gai had to do was Hirudora with it(air from a punch) image what a landed hit from it can do. Lee hasn't be shown in shippuden now is the perfect time to make up for it.
BF Choji- In this mode his strength is...10x??? or was it 100x idk I just know his punches f people up now with Kyuubi chakra it will only be stronger and it Taijutsu so he is able to effect Obito.
Possibly Tenten-...yup I can only imagine the look on some of your faces lol, let me explain. IF she has the Banana fan it should be effective on Obito cause I don't believe it's Ninjutsu after all it is just a tool. She'll be able to do bigger moves and use it longer with Kyuubi chakra to counter and do damage to Obito. Banana fan is arguably the best weapon in the show (side note: I know people like to use her for jokes and stuff but people underrate her potential and it Kishi's fault. He never gave her a good matchup and 1 on 1 so people just see some fodder that can only use ninja tools that aren't great but she's better than people give her credit for)
It's gonna take a lot to beat Obito but these people will be able todo serious damage to him. I think the Nara clan and Ino's clan maybe able to Posses Obito if they work together.