>>28215642>>28215652I hear you.
For me, it was Magnezone. Never really got him in the earlier games, except when I evolved a Magneton into one once in Pearl purely for dex completion before boxing him forever.
But then I caught a Magnemite in Alpha Sapphire and he ended up becoming my de-facto lead. He fried every mon in the ocean's depths while I was chasing Team Aqua and Kyogre. He finished Steven's Mega Metagross after surviving a crit switch-in Giga Impact. And he helped me catch Deoxys when Rayquaza fainted.