Right, Marco should actually be 97% speed I guess (36 of 37)
I take the harshest view of TB speed that I know of, and Mesa is faster than Yulie by my measure.T260G is only that fast if she is willing to forgo decent consistent physical damage (Not a lot of speed, but she'll be slower than Mesa for sure). With the best speed, Pop Knight will be about 1500 damage.
Analysis (apologies for grammer mistakes, because I wrote a lot then realized I needed to edit when I came up with a better strategy)
For the Earth fight, it can Maelstorm first is remove MT (of important note, 50% chance of the team eating mass MT status with near perfect hit rate here), T2 can Magnify...uh...Scar. No wait, Scar has like 1.5 PC HP, that isn't not a successful kill and leads to another 50% MT Status counter. Tengaar already acted, Sasarai has a 50% chance of missing, Delphi won't be killed. So maybe he will Pop Knight. Yulie can Quicken Marco, Delphi Magic Thunder. Now will Marco outrace Sasarai? EQ is 104% speed versus Marco's 97. Delphi is listed as inbetween Dorothy and Scarecrow, but closer to Dorothy (this could be 110% speed). My gut reaction is no. Marco has that small area before Delphi dispels the effect. Then Sasarai does get off EQ. Marco can Trans Turn for another Pop Knight, but Delphi gets another turn which she can use to off Marco I think (Her ST + Earthquake does about 99% damage). This can't be stopped barring Marco switching over to Yulie and Yulie being on revival. Scar can only do damage, but that damage is more than enough to get someone out of the way. If Marco does switch to T2, then I guess Delphi adds .2 MT (about 0.8 total). At this point Scar can kill Yulie with his physical. Next round though...if Mesa does not use healing, Delphi's MT gets too much damage. So counter goes down 1...and then Delphi's still gets Mesa regardless. Counter down 2.
So Marco probably needs to transfer to Yulie, who needs to heal (4/7 this is actually MT). Of course...if he is expecting Yulie to heal, I think Sasarai probably just heals too. So...this is rinse and repeated next round except two things: Scar's damage sticks and Golem is dead. Tengaar CDs...blah blah blah. Cut to it, at the very least, they are blowing MP and Mesa will die at least once.
Taking bigger SD doesn't really help. Tengaar is still going first, Yulie and Marco don't speed up, but Sasarai and Delphi do.
Wind fight: If you see Barby as faster than your team, why doesn't she just phyiscal Yulie and kill her instead of spinning? Or kill Mesa, bring that counter down to 6 (if not lower). Crono of course does 40% MT Lightning magic. Yukari and Tiamat are the same speed as Raynie so...Raynie may need to tiebreak them both (As a reminder, team is probably already riding on a potential 50% mass status from last time very likely). FYI, two Pop Knights will only get Yukari (Barby's PDur is okay, certainly above 1.1, Tiamat is a just a death tank to items that are not Sacrifice, Kanji has like 1.7 Durability overall). Each Pop Knight has a 50% of unleashing low 2HKO Thunder magic of note. Most of these people are getting at least a turn if you see Barby as fast enough (Even if not, she's probably still fast enough to at least get a turn)
Fire fight: Yukiko is weak to Ice in a game with no Water. Mesa's Water is distinctly different than Ice (like a completely wholly different type of check). I don't think I see Yukiko as weak in this case; it's just too big an element split in Saga. This is kind of a big split. Regardless though, Mesa dies at least once unless Yulie wants to hit her with Protect. If you do see Yukiko as weak, Safeguard at least means she does not get knocked down if she evades the first (and there is One Mores if she is not knocked down? And does MT even get one mores unless they are all weak?) So...I find this one a lot messier. Safeguard also means that they need to draw the fight out if they want to do the slow MP healing. Yukiko must be killed first, which...since she evades turn 1 is 4 turns of attacks (1 Evade, 1 Hit, 1 Evade, 1 Hit againstEnduring. And that's assuming that T260G OHKOs with Magnify. This needs Saga elements to hit the weakest element since Yukiko halves Thunder. Then it takes 5 hits. Clear Ice damage is awesome here). So in the meanwhile, that's a somewhat free turn for the enemies to wreak havoc.
On the Water fight, I notice that you are predicating on leaving Mao alive turn 1, but using all your PCs and killing everyone off. This won't work because Mao has MT revival. This is the least problematic fight to me, but killing Marle and Frog and then having Mao revive them a little still is a bit of a setback (Not bad, just forces T2 to use Pop Knight for sure). FYI, Cagnazzo phys+Lenus MT+Kraken phys...does KO damage (Aka: Gets any of the healers). Pop-Knight does about 57% MT damage, so it does not get Marle (The ST physical does though. Marle's Pdur is 60%). Mesa may be dying at least 1 time each match at minimum. They at some point probably have to Sleep Mao early because they can't have her revive others (You also need to assume that dungeon enemies can never hit each other or else they will just kill Mao, which is not unreasonable). Also, Mesa when alive needs to constantly be under Protect. Lenus can kill otherwise. So let's say...Pop-Knight, Maelstorm, Protect Mesa, Marco transfers to T2 to ST off Frog (this...well, would be Pop Knight, but that eliminates Mao so there is not any stalling at the end and hits Lenus into limit range). But Mao can revive Frog and Marle, who need to be taken out individually so at not to activate anything wrong with the MT. Cag/Lenus/Kraken go for Marco.
On the last fight, well, yes, it will help if Mesa hasn't needed to blow Stasis Rune already. But...it will wear off when PD switches form I think. I can't remember what of Kato's was AoE. Lamington and Kato can polish off things...potentially what Kato doing AoE that also status out others. Stasis needs to hit through boss immunities. So...there are a lot of things through out the floor that can really go wrong. There are fights were Mesa can just potentially fall several times. She may not be here at the last time, which leaves PD open to systematically massacre often. I think the team could get here, but there's a lot of ways that the team can fail.
