Which political party Republican or Democrat tends to benefit when incomes increase or decrease in other words which party has more wealthy voters and which party has more poor voters?

Actually, the results are generally opposite of what you supposed. When general incomes go up (that is, the country feels prosperous), the Democratic Party generally seems to benefit. It may be that when people feel "flush" and have a stable income, they seem to favor many of the social equality programs that Democrats champion.

On the other side, during times of depressed incomes (that is, when the overall income levels fall), the Republican Party's mantra of "lower taxes, smaller government" (actually, these days, it's "wasteful government"), seems to resonate, gaining them considerable votes.

However, all of this is a vast over-simplified generalization. The reality is that it is extremely difficult to make predictable statements about long-term trends. Politics in America are very specific to the immediate time - things that work in one election cycle may very well backfire the next one.