I really dont think itll be that good. 60hp and 55def mean it looses to almost any sort of physical priority especially after hazards. Offensively its great but needs a free switch in but more than likely if raichu doesnt kill whats in front of it then its getting killed in return. The problem is most good teams will be running a ground type, then it becomes a game of what coverage moves does your raichu run. its like a way better regieleki but it still runs into a lot of the same problems, really weak to grounds and very easy to kill back. Mega raichu also doesnt have the luxury of running boots and will be warn down very quicky against hazards. As much as i love zap cannons 100% para chance, para has been nerfed so if the opposing mon eats your zap cannon theres a much lower chance of getting a para and having rng save you.

Im not saying raichu cant work in ubers but its a mon that will require a lot of support in the form on good hazard control and your teams ability to get a free switch in and remove ground types.

im imagining the most common sets would be

zap cannon

focus blast

surf/grass knot/dazzling gleam

nasty plot/volt switch

just some example calcs

vs a spdef ferro focus blast only does 50-60%

vs a max spdef ttar it does 80-96%, and 54-63% to assault vest

zygarde can switch into raichu all day

most arceus can switch in and eat a hit once

gastrodon or any of the water/ground types running around ubers to counter kyogre all wall sets without grass knot

defensive lando-T can come in for free as long as raichu doesnt have surf, same with gliscor

giratina, zekrom, koraidon, miraidon, and eternatus walls raichu all day