User blog comment:CrashBash/Crash's Top 10 Turnabouts/@comment-29558956-20170911185011

It would be a no-brainer to mention Bigger Brother vs Hypno-Disc, Series 5, as a potential candidate:

The damage dealt to Bigger Brother was immense, but its resilience eventually paid off as it buffeted and pushed Hypno-Disc around before pitting it. When you consider that Hypno-Disc could've otherwise KO'd Bigger Brother or taken the Judges' decision on damage, I consider that to be an especially significant and endearing turnabout in my books.

Also, Panic Attack vs X-Terminator, Series 3:

Panic Attack's move to rupture X-Terminator's gas canister practically saved it from being dominated by the then-newcomer. As I said before in Ragnabattle, X-Terminator was working towards a GENUINELY major upset by axing, dragging and ramming Panic Attack around, and would've certainly eliminated the defending champion had the canister not ruptured before it was turned onto its side.