Spanish language learning forums - Question about irregular verbs (present tense)

This may be an oddly specific question. I teach a Spanish class and have prepared the Venn diagram linked below to show the relationship between different types of regular and irregular verbs (in the indicative present tense).

Is there a relationship that I am missing? For instance, is there:

1. A verb that both has a regular spelling change (e.g. conoZco) but is also a stem changer (e.g. querer)? This regular spelling change would have to occur in the nosotros/vosotros form (I don't even know if such a verb exists!)

2. A verb that has a regular spelling change, is also a stem changer, and has an irregular yo form (like how vener is both a stem changer and irregular yo verb, but on top of that has a normal spelling change in the nos/vosotros form).

I can't even think of a verb that has just a regular spelling in the nosotros/vosotros form, so I'm guessing the answer to this question is that there aren't any such verbs. I was wondering if there was some obscure verb out there. I want my Venn diagram to be accurate.

https://www.scribd.com/doc/246286799...os-Irregulares