Regidrago vs Regieleki

Pick by the job, not by the total

IGN’s comparison and the two stat pages agree on the spread: both giants have 100 Attack, 50 Defense, 100 Special Attack, and 50 Special Defense. The entire difference is HP versus Speed. Dragon's Maw boosts Regidrago’s Dragon moves by 1.5. Transistor boosts Regieleki’s Electric attacks by 1.5× in Sword/Shield; Scarlet/Violet reduced that multiplier to about 1.3×. Smogon’s SV dex and Bulbapedia’s ability history agree on the generation change. Dragon Energy and Thunder Cage are the signatures. If you want a slow special attacker that soaks a hit, I point at Regidrago. If you want to move first almost every time, I point at Regieleki.

If you already chose

The ruins allow only one of the two encounters per save. You can still own both on that save through trade or a compatible Pokémon HOME transfer. The rescue that two community guides describe is a second Switch profile and a Pokémon HOME transfer. I do not call that an official feature. Collectors can choose the missing giant in a second file, or arrange a trade.

Editor scores, not an official ranking: for a main-series special attacker I give Regidrago the edge when the team lacks a slow Dragon breaker, and Regieleki the edge when the team lacks speed control. In GO raids I refuse a single winner because 14.2 Dragon DPS and 19.6 Electric DPS answer different bosses. For a living dex, neither edge matters: you need a trade or a transfer from another save.