Tyranitar. Anything that could be considered a perfect design should be a stage 2. Evolution is the core of pokemon so a build up leading to a grand conclusion is vital. With T-tar you have the cut lil Larvitar as an ideal first stage. You then have pupitar as the literal mid-stage chrysalis that with enough hard work eventually becomes the beautiful butterfly that is Tyranitar. He's difficult to find meaning you have to search far and wide and reach the heights of a trainer to get him. He's a kaiju which represents early pokemon's design philosophy. He's a pseudo, a long standing part of pokemon's identity. He sees competative success thanks to his ability, unique typing, and vastly customizable movepool creating a microcosm of the competative environment in a single pokemon. He's from the era when pokemon still had soul and represents the swan song of pokemania.

Absolute peak even if he isn't my personal favorite.