going up one step on voltage should never be a problem. Just as long as the cap fits as the higher voltage is normally a little bit larger. I do this a lot on electronic power supplies as a lot of time they are marginal at best.

Voltage on capacitors is a maximum rating. You can always use higher rated voltage as long as the capacitance (uf, mfd, etc) is correct, and of course physical dimensions as sandbagger mentioned.

Going higher in voltage is fine but this normally results in a larger capacitor body. Some are larger diameter and some are taller... and a myriad of combinations of both taller and/or fatter.

Three things to watch out for when replacing these caps:
1 -- lead pitch (spacing between leads). Most use 10mm.
2 -- maximum height of capacitor. Some of the higher voltage caps are taller and some games have problems with caps that are 50mm tall such as NBA Fast Break.
3 -- manufacturer matters. Avoid completely Chinese brands such as G-Luxon, Lelon, Capxon, Teapo, etc. Nearly all electrolytics are made in China now - even many Japanese ones. Difference is - the US and Japanese brands actually enforce quality standards (some more than others) - the Chinese brands only care about quantity and profit.

Ed

Some info that I may offer about replacement caps from experience:
Even though going the next higher voltage rating usually results in a larger capacitor, the capacitor technology has gotten better over the years in that a cap from a 15 year old machine is usually larger than its new replacement counterpart. So the fear of using a 35 volt instead of a 25 volt usually wont result in fitment problems as the new one will be smaller than the original. Not true in all cases, check your local regulations, your mileage may vary.