Is Yolomouse bannable?

No idea what yolomouse does, but here are some posts that go over the use of 3rd party applications so you have some guidelines;

http://boards.na.leagueoflegends.com/en/c/player-behavior-moderation/5dmkJinG-3rd-party-applicationsmodifications-whats-allowed-and-what-isnt

http://boards.na.leagueoflegends.com/en/c/miscellaneous/5kx4F7VE-reminder-third-party-applications

FYI, there's a riot post here:

https://boards.euw.leagueoflegends.com/en/c/aiuto-e-supporto-it/w2Em8J1e-richiesta-chiarimento-puntatore-mouse-personalizzato?comment=0004

where this person says:

Quindi se Yolomouse modifica solo l'aspetto del tuo puntatore questo non porta ad un ban, ma come ti abbiamo detto tramite il supporto, fai sempre attenzione ai programmi di terze parti, perché noi non abbiamo alcun controllo su di loro e non possiamo assicurare che il gioco funzioni correttamente se le utilizzi.

which translates to:

So if Yolomouse only modifies your pointer's appearance this does not lead to a ban, but as we said through support, always pay attention to third-party programs because we have no control over them and we can not ensure that The game works properly if you use it.