If 148 plays like they did in St. Louis and New Orleans, it would be very very very tough (especially if they have the St. Louis hybrid). If they play like they did at Championship, the alliance is very beatable (as shown by the multiple times they flirted with disaster). Either way, there are a number of alliance structures that would be able to pressure the alliance, and a few alliances that can even run-and-gun with them.
I won't go into too much detail, but the keys are fast and effective hurdling, ball control, and keeping it close in hybrid.
The Poof/RAWC twins are perhaps the most dangerous teams to the 1114/217/148 alliance, as they can hang with 1114's scoring, and are quick and agile enough to make it very hard for 148's defensive style to work against them. There are others who could be very trouble-some in this role, such as 27(fully working), 39, 103, or 330. 148 will have a much easier time hindering those three though. 968 and 103 are the only ones who can even come close of these four to matching 1114's hybrid scoring, which means the partners will have to pick up some slack. If a team like 1124 or 365 takes the 2nd slot, with their ability to get and score the trackball while defended and huge hybrid points can compliment the first member extraordinarily well.
The third member will make or break the alliance. 1114 and 217 can both acquire the ball in stick situations, and 1114 made a living of sneaking balls out of corners and seemingly impossible situations. A simple "corner-lock" is very hard to pull off successfully against them without allocating too much scoring. The third partner needs to be able to put up hybrid points, lap quickly, and hamper the opponent's scoring.
201 is the ultimate X-Factor, as when they were on their game, they were a defender without peers. Their ball-driving defense cut down 217's scoring at GLR elims, and held 27 to a single hurdle in an elimination match on Galileo. Other matches they were absolutely abused though. They can even chip in a hurdle if needed.
Other than 201, a few other legitimate possibilities exist. 8 was looked at as the "designated simbot stopper" on Galileo, although 1114 went 3-0 against them. In the right alliance and in a great match they could apply enough pressure. A strong combo-threat like 494/70, 68, or 1771 could also make a difference as the third partner.
There's a lot more to the match-up and game strategy I could go into, but I won't tip my hand too much...
The alliance with the best shot, imho, would be 968/1124/201.