Jamie Madrox + Rahne Sinclair = Wolfpack (mutant girl turns an entire pack of wolves)

Pete Wisdom + Kitty Pryde = Burn (tuns into a hot plasma entity, practically a living lightning bolt)

Gambit + Rogue = Sanguine (life-force vampire, drains people's vitality and knocks them out to boost her own strength, stamina, speed, etc. like La Lunatica of the X-Men 2099)