Sentinel have a lot of 8 power equivalents, which allows them to do fine with their bonus blocked. All Stars have a lot of 7 powers and high utility with cards that can serve multiple functions, like Saki, Marina, Karen, etc. Uppers suffer more from SoA than anything else; without their bonuses most of their cards are still very solid for their star level. Sakrohm do have a problem with this, which is why they are also unpopular in ELO unless Uranus is unbanned.
+2 Power type clans are the ones who are in the most awkward position, generally speaking. If you give a 2* or 3* 6 power, they are at a huge disadvantage against SoB. If you give them 7 power, they are at a considerable advantage when they are not against SoB. You can't give a 3* 7/5 base stats, as that would generally be overpowered... So any high-gap low * cards in a +power clan have to be extremely reliant on their abilities, or have 6 power or less.
Take a look at Ulu Watu's George, who is one of their best 3* gappers. Without bonus, he becomes a virtual 7/5. Not great, but not bad. Without ability, he becomes a 9/3 wall -- not what you want from your 3*s, as the damage is too low, and he still needs to be pilled relatively high to block a strong card. Compare him to Uppers' Oxen: a virtual 7/6 without bonus (although with a high min) and a 7/3 with -10 attack min 3 without ability. He is suitable for forcing pills, and a better low-pill wall than George. It takes George 5 pills to catch up to Oxen.