That depends: fusion does not exclude regularity, especially if analogy works its magic along the line.
Given intransitive agreement markers
ma-,
ti-,
sol- corresponding to three noun classes, the following combinations for transitive agreement could occur:
| ma- | ti- | sol- |
ma- | mã- | mak- | maad- |
ti- | tĩ- | tik- | tiid- |
sol- | sũ- | suk- | suud- |
What we see here is that
ma- is always reduced to nasalisation,
ti- to -
k- and
sol- to lengthening + -
d-; additionally, the latter always has the form
su- when before another formant.
But a larger degree of fusion could also mean that some combinations become homophonous. In Italian, for example, the six persons are distinguished from one another in all TAM, except in the subjunctive present, where all singular forms have the same ending, and the subjunctive imperfect, where 1sg and 2sg are the same: in these cases, pronouns are compulsory. You could also have disambiguating clitics somewhere on the verbal complex, if full pronouns are too much.
So given the same markers with a different outcome:
| ma- | ti- | sol- |
ma- | mã- | mat- | mat- |
ti- | tĩ- | tit- | tit- |
sol- | sũ- | sut- | sut- |
The last two columns could be distinguished with clitics -
ti and -
su respectively after the verbal complex.
Last possibility: if you are intent to keep fusion irregular, you could keep the number of combinations down with a direct-inverse system, so that there is only one affix for any combination of class markers and persons. Your noun classes look like they could lend themselves well to a hierarchy.
That's the Algonquin strategy to an extent (no really noun classes there, but different affixes and combinations of affixes depending on the animacy of the participants and TAM marking).
With our made-up markers again:
| ma- | ti- | sol- |
ma- | mã- | mak- | maad- |
ti- | mak- | tik- | tiid- |
sol- | maad- | tik- | suud- |
Here the hierarchy is
ma- >
ti- >
sol-, more exactly the hierarchy between whatever class they're standing for.