farm monthly event cats like eggy, killer, maiden, koi, ect. and grind XP to level em to 30 each, is the main way I do it. alternatively you can buy special cats for UR once they're on sale since they're really cheap to upgrade
Do XP megablitz and upgrade your cheap stuff like the li'l cats for the fastest way. Try keeping a consistent level for all cats (ex: level 10-15 for rares) to be upgraded if all your important cats are maxed already.
sure you already know this, but when you have a bunch of cats to upgrade, upgrade them each equally, like get them all to lvl 2 before getting them all to lvl 3, etc., it will lower xp cost and give you the most user rank for your xp
Best ways to get xp: xp megablitz/colosseum with radar n’ xp up
correct. also do gacha if you want new cats
I think the easiest way to level up crazed cat to level 30 is grinding XP stages ( Exam: XP megablitz, fianl stage of the normal XP stage,etc ) and use the XP on cat that have awaken form (maiden cat, koi cat,etc ) or use them on lil cats (lil cat, lil tank, lil axe,etc ). And i think that the easiest way to upgrade and reach UR 3650