Flanking is a triggered ability that reduces the toughness (and power) of blocking creatures, not the flanking creature itself. Per CR 702.25a, whenever a creature with flanking becomes blocked by a creature without flanking, the blocking creature gets -1/-1 until end of turn. The flanking creature's own stats are completely unaffected.
When a creature with flanking is blocked by multiple creatures, flanking triggers once for each blocking creature that lacks flanking (CR 702.25b). Each trigger is independent, and each non-flanking blocker receives -1/-1 until end of turn from its own trigger. The attacker keeps its full power and toughness throughout.
If all blockers happen to also have flanking, none of the triggers fire at all for those creatures, since the ability only triggers when blocked by a creature without flanking.
Concrete example: Your 2/2 creature with flanking attacks and is blocked by three 2/2 creatures that lack flanking. Flanking triggers three times — one for each blocker. Each blocker becomes a 1/1 until end of turn. Your 2/2 flanker remains a 2/2.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.