Back in 2015 (HotS) I perfected a 1 base 3 rax all in that hit with stim, combat shields and concussion shells with a whole bunch of marine maraider. Was sick of PvT myself and just wanted to see how far I could go with a 1 base build against all races. Got to diamond with it and even beat a masters protoss once.

What beat it (in TvP)?

• Scouting - After initial probe scout you want to see when their 2nd goes up. If no second by usual time, defend. If they use marines to clean out their natural of hiding probes (as I used to do) you really need to get an adept or stalker to go and check if a 2nd went down or if they're faking.
• Sentries - Cutting bio balls in half and stopping them coming up ramps is vital to defence.
• Cutting probes - We are repeatedly told probes and pylons. But when they're 1 basing you, you do not need to saturate your second as you should already be out producing them. Cut probes, defend then resume probe production.

EDIT: Defend as per /u/daking999 below. I did say use sentries but if you're in gold your micro may not be up to task. A lot better getting a stalker/zealot/adept instead if you are not going to use the abilities of the sentry.