There’s a remaster of the first 2 games (Monster Rancher 1 & 2 DX) on Steam, Switch, iOS and release a couple years back.
MR2 has a huge competitive scene, with lots of community run tournaments. it’s even going to be at Combo Breaker, a fairly large annual event/competition for fighting games!
There’s a Spinoff/Crossover game “Ultra Kaiju Monster Rancher” released just over a year ago, where instead of traditional monsters, you raise giant Kaiju from the Ultraman franchise. (Switch only)
There’s a Japanese only mobile gacha game LINE:Monster Farm that’s hugely popular atm
Monster Rancher is alive and kicking!