Still using monitor on DD1 who is 4, she's upstairs and we wouldn't hear her. Also useful as an intercom if she is playing up there (it has talkback).
DD2 ditched the high chair at 18 mo, she's in a booster and at 21 months is desperate to use her sister's Ikea junior chair (but she falls off it occasionally so persisting with the booster)
We took the sides off DD1's cot at 3 when she asked. DD2 still in cot at 21months, no hurry to put her in a bed, it's big and she is short so hoping she won't be able to climb out for a while.
Buggy - DD1 still in it sometimes at 4 but she has mobility issues and gets tired very easily. DD2 starting to refuse it already at 21mo, loves the buggyboard though so we end up with them the "wrong way round" quite often.
Nappies - DD1 day trained about 2.5 (too early, didn't really get it till 2.8). Still in night nappies at 4, no hurry to train as she's a bad sleeper and don't want to give her a reason to wake iyswim.
Stairgates could probably go now at 21mo, but will be on for a while just in case, as we have long flights of stairs and a very hard floor at the bottom.
General theme is that DD2 wants to be like her big sister so is refusing all baby accoutrements very early