First, I would like to say that I have found no page for debuff success (both debuff success [boosted] buff and debuff success [lowered] debuff [debuff does not exist yet] sections probably under the said page or reference each other). I apologize in advance there is one already. The below text is just some information for the impending page. The true purpose of this topic is to spur forth at least a starting guide in overriding same element debuff resistance. Pretty hefty challenge if you ask me.
We know that 
Mithra is the high par in debuff success of 25%, applying to all allies. However, due to the elemental strong(+50%)/neutral(0%)/weak(-25%)/same(-50%) (damage and debuff success rate) penalty, it itself may not be enough.
Are there other characters, weapons, summons that could replace or contribute to that 25%? I see a vague plenty, but so far, the record keeping has been too overwhelmed to watch over the said pages. I cannot be so sure about it.
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Can 
Debuff Success BoostedDebuff success rate is boosted
like 
Danua (Summer)'s Fear Domain support skill be helpful in same element situations? Same might go for 
Korwa's Noir et Blanc skill. Some people might look for 
Laguna's Omar's Wisdom skill as possibly the highest in debuff success boost (above characters, weapons, and summons), but of course, her 
Omar's OdysseyStatus boosted based on number of turns passed
buff requires a couple of turns. 
Turpin Spear's One Star-Soaring Show weapon skill (level 150 required), 
Sharom Bow's Amethyst's Grace weapon skill, and 
Cosmic Harp SPEC's Special Stance weapon skill can also be passive debuff success boosters.
Somewhat off-topic to boosting debuff success, can lowering debuff resistance like 
Drang's Fair Trick skill, be helpful as well? 
Goblin Mage's Extended Mastery support skill, while not throughout constant in implementation, may inflict by chance per turn. On the other hand, 
Cerberus is a good example of lowering debuff resistance in Absorption skill and Infernal Heaven support skill. This being a debuff, how much debuff success rate is required to inflict 
Debuff Res. DownDebuff resistance is lowered
compared to other debuffs?
And one more thing, debuff success is intended for battle situations. It might mean a quicker way to land bounties to Bounties just increase the number of chests in loot (for loot or item drop situations, not battle situations); therefore, the 
Bounty lvl 9Item drop rate is boosted
, but that gold chest can pop out of nowhere at any time!
BountyItem drop rate is boosted
status is not a debuff and the quantity has a upper limit. If you want that rare item from a battle, expect to toil endlessly for it. That means just to fight the foe numerous times with a fair enough drop rate percentage.