Regulation M-B's two most-discussed additions are Mega Metagross and Mega Swampert. Both are strong. Both will appear at Worlds 2026. But they are not interchangeable — they solve different problems and demand different team structures.
Mega Metagross is the safer, more self-sufficient pick. Base 110 Speed is the headline number — it lets Metagross outpace Mega Charizard Y, Garchomp, and most of the M-A roster that previously had free rein in the upper speed tiers. It pairs that speed with higher defences than almost any other Mega in the format, and a movepool wide enough to cover most relevant threats. Mega Metagross does not need team support to function. It can be dropped onto many existing structures and immediately improve them.
Mega Swampert is conditional but potentially more explosive. Speed Boost means every turn it survives, it gets faster. Wave Crash is a high-power physical Water move that hits exceptionally hard. The catch: Speed Boost is most threatening under Rain, where Wave Crash also gets a 50% power boost from weather. Mega Swampert without Rain support is still viable, but not at the same ceiling. You are building around Swampert more than you are just slotting it in.
The correct choice depends on your team. If you are running Rain and have Pelipper or another weather setter, Mega Swampert in that structure has a higher damage ceiling than Mega Metagross. If you are running a balanced or offensive team without a weather core, Mega Metagross fits more cleanly and brings its own speed without needing turns to accumulate.
Both have a valid Worlds argument. The teams built around them will look very different.
Compare their full stats in the Pokémon database.