It should be warm in July so I suggest you just layer clothes. Take a light waterproof jacket to put over the top. If you're concerned about the cold you could take a hat and gloves but you might just as easily need a sunhat. I would think that runners/joggers would be fine at that time of year unless you are hiking in the snow. As long as you can change wet shoes into dry you shouldn't have a problem. I suggest sunglasses even for Junior.

Shoes with traction.

There's nothing more entertaining than watching an ill-equipped tourist slide around on the snow in their city shoes...some of these mountains (like the Jungfrau) have snow year round.

There may be some snow on the peaks, but the paths from the cable car station to observations platforms are easy to walk and usually kept free of snow. Especially during summer you should not expect any problems. And no, you can't rent shoes at the top.

But most major brands for running shoes like Adidas also have a line of shoes for hiking.
They look like regular runners but have good traction and should have some gore-tex to be water resistant. These are also much better to explore cities or towns and walk miles on cobblestones than "nice shoes" or regular running shoes.

Agree with Cowboy. And what sort of excursion are you planning? With a 25month old and doing every day a mountain excursion with trains and cable cars, I'd guess you will be doing general tourist stuff, no hiking involved. Then as cowboy wrote, the paths to the obseravation decks are all well prepared (often even for - not too fancy - city shoes) and you would have no problem. As to the clothes, as others wrote, layers. At the worst case with bad wheather, there are indoor areas at the top where you can stay warm.

Thanks guys for the Info

Datta, your little one will LOVE the snow that should still be at the top of the mountains in July.

When we were in Zermatt (mid July), we took a cable car up to get a close view of the Matterhorn – beautiful site on a clear day.

A young family from South Africa was in our group. The father and his ten year old son suddenly ran off the path and started rolling around in the snow. They had a ball!

Coming from New England it was fun to watch folks enjoy themselves who had never seen snow. I don’t recall it being that cold either. I was though briefly uncomfortable at such a high altitude but that soon passed.

You will love Switzerland…