Man why do yall think rilla is bad to begin with, I really don't get it. The rilla hatred is crazy. Wdym pecharunt doesn't like knock?? Wdym the only reason to use it is glide? I'm not even talking about some magical new set I came up with, I have found plenty of success simply with band by building around it correctly.
Take
this game last week in smogtour r4. While lots of mons may resist glide with their base typing, being able to revenge kill mons that used tera to try and sweep is super important that glide can do for you. In this replay it was tera ice kyurem, but this has also worked vs tera ghost/fairy/ground rmoon, tera ghost/fairy/dark kingambit, tera ghost/elec ival, tera ground/fairy moth, tera fairy bolt (which you can also wood hammer if you're healthy enough to live thunderclap), etc. CB rilla+grassy seed bolt was a core I designed early in SPL to handle basically every rmoon and have a good MU vs those HOs, and it worked quite well! Of course, it's not just about revenge killing things from full. There were several points in the game where it was able to force a revenge kill with strong prio, like on turn 17.
Also look at
this game vs INSULT in OST r5 (this team was undefeated in OST btw). Rilla itself didn't do that much, but that leads into my next point: Grassy terrain is really good, and you can use it to support some great mons like grassy seed bolt and LO zama in my case. These are pokemon that are already good that are just tweaked to benefit from terrain, similar to grassy seed NP ghold. Remember the rilla/garg/ghold/ace/lando/darkrai team that ctc made last year that took over wcop pools? Rilla was obviously central to that team. Lefties garg and lefties darkrai got gross amts of passive healing, but you can also use it to try and make more niche threats work, like grassy seed hawlucha. Grassy terrain is by far the best terrain in SV largely thanks to how good its setter is, but the extra healing/grassy seed proc can boost or create tons of threats.
That's not even accounting for the natural ability to weaken eq that can pair well with certain mons like iron crown. While it does technically also weaken eq for mons like bolt/ghold/gambit, I rate those slightly lower bc they're vulnerable to HLR, unlike crown which is faster than tusk and kills. Suddenly your crown can afford to stay in on lando and ting-lu and throw out another specs tachyon cutter so they're chipped for your bolt and zama in the back.
Point is, build around grassy terrain with powerful wincons and lean into rilla's ability to force knocks on birds or draw in certain mons and U-turn on them. Rilla has useful offensive and defensive utility (switching into ting-lu 2+ times is great) and don't get tunnel visioned on it being useless just bc you fight a grass resist like pecharunt or corv. Some grass "resists" like dragapult and torn-t will drop to wood hammer after rocks or any chip, glowking is cleanly 2hko'd. If that fails, GF gave you the ability to U-turn so click it correctly and you'll do great.