In alpha decay (electron emission), the particles emitted along with electron is anti-neutrino. On the other hand, the particles emitted by beta decay (positron emission), is neutrino. Neutrino and anti-neutrino are anti-particle pair. There is particle anti-particle pair for each particle. Even electron has a antiparticle - positron. So, what is the anti-particle for proton?
In answer to your question
So, what is the anti-particle for proton?
The following visual guide from the blog article Why Making Neutral Antimatter is Such A Big Deal! is helpful in this regard:
It's called the antiproton. You can literally google "proton antiparticle".