- UFOroid Fighter
- Ultimate Dart Striker
- Ultimate Flare
- Ultimate Offering
- Ultimate Tyranno
- Ultra C
- Ultra Evolution Pill
- Uluru the Guardian Spirit
- Uluru's Guardian
- Umi
- Unacceptable Result
- Underground Arachnid
- Underworld Circle
- Uni-Horned Familiar
- Unibird
- Unicycular
- Unknown Synchron
- Upgrade
- Upshift
- Upstart Goblin
- Urgent Tuning
- Uria, Lord of Searing Flames
- Utopian Hope
- V-Tiger Jet